Author: "Alconada Verzini, MJ" - Searchworks@Jio Institute Digital Library Search Results

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3,158 results on '"Alconada Verzini, MJ"'

1. Search for single vector-like B quark production and decay via B → bH(bb¯) in pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, Arena, E, Arguin, J-F, Argyropoulos, S, and Arling, J-H
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Vector-Like Quarks, Beyond Standard Model, Exotics, Hadron-Hadron Scattering, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search is presented for single production of a vector-like B quark decaying into a Standard Model b-quark and a Standard Model Higgs boson, which decays into a (Formula presented.) pair. The search is carried out in 139 fb−1 of (Formula presented.) TeV proton-proton collision data collected by the ATLAS detector at the LHC between 2015 and 2018. No significant deviation from the Standard Model background prediction is observed, and mass-dependent exclusion limits at the 95% confidence level are set on the resonance production cross-section in several theoretical scenarios determined by the couplings cW, cZ and cH between the B quark and the Standard Model W, Z and Higgs bosons, respectively. For a vector-like B occurring as an isospin singlet, the search excludes values of cW greater than 0.45 for a B resonance mass (mB) between 1.0 and 1.2 TeV. For 1.2 TeV < mB< 2.0 TeV, cW values larger than 0.50–0.65 are excluded. If the B occurs as part of a (B, Y) doublet, the smallest excluded cZ coupling values range between 0.3 and 0.5 across the investigated resonance mass range 1.0 TeV < mB< 2.0 TeV.
Published: 2023

2. Search for new phenomena in final states with photons, jets and missing transverse momentum in pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Arcangeletti, C
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Beyond Standard Model, Hadron-Hadron Scattering, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for new phenomena has been performed in final states with at least one isolated high-momentum photon, jets and missing transverse momentum in proton–proton collisions at a centre-of-mass energy of s = 13 TeV. The data, collected by the ATLAS experiment at the CERN LHC, correspond to an integrated luminosity of 139 fb−1. The experimental results are interpreted in a supersymmetric model in which pair-produced gluinos decay into neutralinos, which in turn decay into a gravitino, at least one photon, and jets. No significant deviations from the predictions of the Standard Model are observed. Upper limits are set on the visible cross section due to physics beyond the Standard Model, and lower limits are set on the masses of the gluinos and neutralinos, all at 95% confidence level. Visible cross sections greater than 0.022 fb are excluded and pair-produced gluinos with masses up to 2200 GeV are excluded for most of the NLSP masses investigated. [Figure not available: see fulltext.].
Published: 2023

3. Search for boosted diphoton resonances in the 10 to 70 GeV mass range using 138 fb−1 of 13 TeV pp collisions with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, and Arena, E
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, Beyond Standard Model, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for diphoton resonances in the mass range between 10 and 70 GeV with the ATLAS experiment at the Large Hadron Collider (LHC) is presented. The analysis is based on pp collision data corresponding to an integrated luminosity of 138 fb −1 at a centre-of-mass energy of 13 TeV recorded from 2015 to 2018. Previous searches for diphoton resonances at the LHC have explored masses down to 65 GeV, finding no evidence of new particles. This search exploits the particular kinematics of events with pairs of closely spaced photons reconstructed in the detector, allowing examination of invariant masses down to 10 GeV. The presented strategy covers a region previously unexplored at hadron colliders because of the experimental challenges of recording low-energy photons and estimating the backgrounds. No significant excess is observed and the reported limits provide the strongest bound on promptly decaying axion-like particles coupling to gluons and photons for masses between 10 and 70 GeV. [Figure not available: see fulltext.]
Published: 2023

4. Search for dark matter produced in association with a dark Higgs boson decaying into W+W− in the one-lepton final state at s = 13 TeV using 139 fb−1 of pp collisions recorded with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aoki, T, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, and Arena, E
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Dark Matter, Hadron-Hadron Scattering, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: Several extensions of the Standard Model predict the production of dark matter particles at the LHC. A search for dark matter particles produced in association with a dark Higgs boson decaying into W+ W− in the ℓ±νqq¯′, final states with ℓ = e, μ is presented. This analysis uses 139 fb −1 of pp collisions recorded by the ATLAS detector at a centre-of-mass energy of 13 TeV. The W± → qq′ ¯ decays are reconstructed from pairs of calorimeter-measured jets or from track-assisted reclustered jets, a technique aimed at resolving the dense topology from a pair of boosted quarks using jets in the calorimeter and tracking information. The observed data are found to agree with Standard Model predictions. Scenarios with dark Higgs boson masses ranging between 140 and 390 GeV are excluded. [Figure not available: see fulltext.].
Published: 2023

5. Search for heavy resonances decaying into a Z or W boson and a Higgs boson in final states with leptons and b-jets in 139 fb−1 of pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aoki, T, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, and Arce, ATH
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, Beyond the Standard Model Searches, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: This article presents a search for new resonances decaying into a Z or W boson and a 125 GeV Higgs boson h, and it targets the νν¯ bb¯ , ℓ+ℓ−bb¯ , or ℓ±νbb¯ final states, where ℓ = e or μ, in proton-proton collisions at s = 13 TeV. The data used correspond to a total integrated luminosity of 139 fb−1 collected by the ATLAS detector during Run 2 of the LHC at CERN. The search is conducted by examining the reconstructed invariant or transverse mass distributions of Zh or Wh candidates for evidence of a localised excess in the mass range from 220 GeV to 5 TeV. No significant excess is observed and 95% confidence-level upper limits between 1.3 pb and 0.3 fb are placed on the production cross section times branching fraction of neutral and charged spin-1 resonances and CP-odd scalar bosons. These limits are converted into constraints on the parameter space of the Heavy Vector Triplet model and the two-Higgs-doublet model. [Figure not available: see fulltext.].
Published: 2023

6. Differential tt¯ cross-section measurements using boosted top quarks in the all-hadronic final state with 139 fb−1 of ATLAS data

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Arcangeletti, C
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, Hadron-Hadron Scattering, Jet Substructure and Boosted Jets, Top Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: Measurements of single-, double-, and triple-differential cross-sections are presented for boosted top-quark pair-production in 13 TeV proton–proton collisions recorded by the ATLAS detector at the LHC. The top quarks are observed through their hadronic decay and reconstructed as large-radius jets with the leading jet having transverse momentum (pT) greater than 500 GeV. The observed data are unfolded to remove detector effects. The particle-level cross-section, multiplied by the tt¯ → WWbb¯ branching fraction and measured in a fiducial phase space defined by requiring the leading and second-leading jets to have pT> 500 GeV and pT> 350 GeV, respectively, is 331 ± 3(stat.) ± 39(syst.) fb. This is approximately 20% lower than the prediction of 398−49+48 fb by Powheg+Pythia 8 with next-to-leading-order (NLO) accuracy but consistent within the theoretical uncertainties. Results are also presented at the parton level, where the effects of top-quark decay, parton showering, and hadronization are removed such that they can be compared with fixed-order next-to-next-to-leading-order (NNLO) calculations. The parton-level cross-section, measured in a fiducial phase space similar to that at particle level, is 1.94 ± 0.02(stat.) ± 0.25(syst.) pb. This agrees with the NNLO prediction of 1.96−0.17+0.02 pb. Reasonable agreement with the differential cross-sections is found for most NLO models, while the NNLO calculations are generally in better agreement with the data. The differential cross-sections are interpreted using a Standard Model effective field-theory formalism and limits are set on Wilson coefficients of several four-fermion operators. [Figure not available: see fulltext.].
Published: 2023

7. Measurement of the top-quark mass using a leptonic invariant mass in pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adachi, S, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alshehri, AA, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, CF, Anders, JK, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aperio Bella, L, Araque, JP, Araujo Ferraz, V, Araujo Pereira, R, Arcangeletti, C, and Arce, ATH
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, Hadron-Hadron Scattering, Top Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A measurement of the top-quark mass (mt) in the tt¯ → lepton + jets channel is presented, with an experimental technique which exploits semileptonic decays of b-hadrons produced in the top-quark decay chain. The distribution of the invariant mass mℓμ of the lepton, ℓ (with ℓ = e, μ), from the W-boson decay and the muon, μ, originating from the b-hadron decay is reconstructed, and a binned-template profile likelihood fit is performed to extract mt. The measurement is based on data corresponding to an integrated luminosity of 36.1 fb−1 of s = 13 TeV pp collisions provided by the Large Hadron Collider and recorded by the ATLAS detector. The measured value of the top-quark mass is mt = 174.41 ± 0.39 (stat.) ± 0.66 (syst.) ± 0.25 (recoil) GeV, where the third uncertainty arises from changing the Pythia8 parton shower gluon-recoil scheme, used in top-quark decays, to a recently developed setup. [Figure not available: see fulltext.].
Published: 2023

8. Search for direct pair production of sleptons and charginos decaying to two leptons and neutralinos with mass splittings near the W-boson mass in s = 13 TeV pp collisions with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, Arena, E, and Arguin, J-F
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, Supersymmetry, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for the electroweak production of pairs of charged sleptons or charginos decaying into two-lepton final states with missing transverse momentum is presented. Two simplified models of R-parity-conserving supersymmetry are considered: direct pair-production of sleptons (ℓ~ ℓ~) , with each decaying into a charged lepton and a χ~10 neutralino, and direct pair-production of the lightest charginos (χ~1±χ~1∓) , with each decaying into a W-boson and a χ~10 . The lightest neutralino (χ~10) is assumed to be the lightest supersymmetric particle (LSP). The analyses target the experimentally challenging mass regions where m(ℓ~)−m(χ~10) and m(χ~1±)−m(χ~10) are close to the W-boson mass (‘moderately compressed’ regions). The search uses 139 fb −1 of s = 13 TeV proton-proton collisions recorded by the ATLAS detector at the Large Hadron Collider. No significant excesses over the expected background are observed. Exclusion limits on the simplified models under study are reported in the (ℓ~χ~10) and (χ~1±χ~10) mass planes at 95% confidence level (CL). Sleptons with masses up to 150 GeV are excluded at 95% CL for the case of a mass-splitting between sleptons and the LSP of 50 GeV. Chargino masses up to 140 GeV are excluded at 95% CL for the case of a mass-splitting between the chargino and the LSP down to about 100 GeV. [Figure not available: see fulltext.]
Published: 2023

9. Measurement of electroweak Zνν¯γjj production and limits on anomalous quartic gauge couplings in pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aoki, T, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, and Arena, E
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Electroweak Interaction, Hadron-Hadron Scattering, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: The electroweak production of Z(νν¯) γ in association with two jets is studied in a regime with a photon of high transverse momentum above 150 GeV using proton–proton collisions at a centre-of-mass energy of 13 TeV at the Large Hadron Collider. The analysis uses a data sample with an integrated luminosity of 139 fb−1 collected by the ATLAS detector during the 2015–2018 LHC data-taking period. This process is an important probe of the electroweak symmetry breaking mechanism in the Standard Model and is sensitive to quartic gauge boson couplings via vector-boson scattering. The fiducial Z(νν¯) γjj cross section for electroweak production is measured to be 0.77−0.30+0.34 fb and is consistent with the Standard Model prediction. Evidence of electroweak Z(νν¯) γjj production is found with an observed significance of 3.2σ for the background-only hypothesis, compared with an expected significance of 3.7σ. The combination of this result with the previously published ATLAS observation of electroweak Z(νν¯) γjj production yields an observed (expected) signal significance of 6.3σ (6.6σ). Limits on anomalous quartic gauge boson couplings are obtained in the framework of effective field theory with dimension-8 operators. [Figure not available: see fulltext.].
Published: 2023

10. Cross-section measurements for the production of a Z boson in association with high-transverse-momentum jets in pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, Arena, E, and Arguin, J-F
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, Electroweak Interaction, Hadron-Hadron Scattering, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: Cross-section measurements for a Z boson produced in association with high-transverse-momentum jets (p T ≥ 100 GeV) and decaying into a charged-lepton pair (e + e − , μ + μ −) are presented. The measurements are performed using proton–proton collisions at s = 13 TeV corresponding to an integrated luminosity of 139 fb −1 collected by the ATLAS experiment at the LHC. Measurements of angular correlations between the Z boson and the closest jet are performed in events with at least one jet with p T ≥ 500 GeV. Event topologies of particular interest are the collinear emission of a Z boson in dijet events and a boosted Z boson recoiling against a jet. Fiducial cross sections are compared with state-of-the-art theoretical predictions. The data are found to agree with next-to-next-to-leading-order predictions by NNLOjet and with the next-to-leading-order multi-leg generators MadGraph5_aMC@NLO and Sherpa. [Figure not available: see fulltext.].
Published: 2023

11. Measurement of single top-quark production in the s-channel in proton–proton collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aoki, T, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, and Arena, E
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, Top Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A measurement of single top-quark production in the s-channel is performed in proton–proton collisions at a centre-of-mass energy of 13 TeV with the ATLAS detector at the CERN Large Hadron Collider. The dataset corresponds to an integrated luminosity of 139 fb −1. The analysis is performed on events with an electron or muon, missing transverse momentum and exactly two b-tagged jets in the final state. A discriminant based on matrix element calculations is used to separate single-top-quark s-channel events from the main background contributions, which are top-quark pair production and W-boson production in association with jets. The observed (expected) signal significance over the background-only hypothesis is 3.3 (3.9) standard deviations, and the measured cross-section is σ=8.2−2.9+3.5 pb, consistent with the Standard Model prediction of σSM=10.32−0.36+0.40 pb. [Figure not available: see fulltext.]
Published: 2023

12. Search for light long-lived neutral particles that decay to collimated pairs of leptons or light hadrons in pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, and Arce, ATH
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Exotics, Hadron-Hadron Scattering, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for light long-lived neutral particles with masses in the O(MeV–GeV) range is presented. The analysis targets the production of long-lived dark photons in the decay of a Higgs boson produced via gluon–gluon fusion or in association with a W boson. Events that contain displaced collimated Standard Model fermions reconstructed in the calorimeter or muon spectrometer are selected in 139 fb−1 of s = 13 TeV pp collision data collected by the ATLAS detector at the LHC. Background estimates for contributions from Standard Model processes and instrumental effects are extracted from data. The observed event yields are consistent with the expected background. Exclusion limits are reported on the production cross-section times branching fraction as a function of the mean proper decay length cτ of the dark photon, or as a function of the dark-photon mass and kinetic mixing parameter that quantifies the coupling between the Standard Model and potential hidden (dark) sectors. A Higgs boson branching fraction above 1% is excluded at 95% CL for a Higgs boson decaying into two dark photons for dark-photon mean proper decay lengths between 10 mm and 250 mm and dark photons with masses between 0.4 GeV and 2 GeV. [Figure not available: see fulltext.].
Published: 2023

13. Measurement of the tt¯ production cross-section in pp collisions at s = 5.02 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aoki, T, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, and Arena, E
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, Hadron-Hadron Scattering, Top Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: The inclusive top-quark pair (tt¯) production cross-section σtt¯ is measured in proton–proton collisions at a centre-of-mass energy s = 5.02 TeV, using 257 pb−1 of data collected in 2017 by the ATLAS experiment at the LHC. The tt¯ cross-section is measured in both the dilepton and single-lepton final states of the tt¯ system and then combined. The combination of the two measurements yields σtt¯=67.5±0.9(stat.)±2.3(syst.)±1.1(lumi.)±0.2(beam)pb, where the four uncertainties reflect the limited size of the data sample, experimental and theoretical systematic effects, and imperfect knowledge of both the integrated luminosity and the LHC beam energy, giving a total uncertainty of 3.9%. The result is in agreement with theoretical quantum chromodynamic calculations at next-to-next-to-leading order in the strong coupling constant, including the resummation of next-to-next-to-leading logarithmic soft-gluon terms, and constrains the parton distribution functions of the proton at large Bjorken-x. [Figure not available: see fulltext.]
Published: 2023

14. Exclusive dielectron production in ultraperipheral Pb+Pb collisions at sNN = 5.02 TeV with ATLAS

Author: Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, and Arena, E
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Heavy Ion Experiments, Heavy-Ion Collision, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: Exclusive production of dielectron pairs, γγ → e + e −, is studied using Lint = 1.72 nb−1 of data from ultraperipheral collisions of lead nuclei at sNN = 5.02 TeV recorded by the ATLAS detector at the LHC. The process of interest proceeds via photon–photon interactions in the strong electromagnetic fields of relativistic lead nuclei. Dielectron production is measured in the fiducial region defined by following requirements: electron transverse momentum pTe > 2.5 GeV, absolute electron pseudorapidity |η e | < 2.5, dielectron invariant mass mee > 5 GeV, and dielectron transverse momentum pTee < 2 GeV. Differential cross-sections are measured as a function of mee, average pTe , absolute dielectron rapidity |yee|, and scattering angle in the dielectron rest frame, |cos θ *|, in the inclusive sample, and also with a requirement of no activity in the forward direction. The total integrated fiducial cross-section is measured to be 215±1(stat.)−20+23(syst.)±4(lumi.) μb. Within experimental uncertainties the measured integrated cross-section is in good agreement with the QED predictions from the Monte Carlo programs Starlight and SuperChic, confirming the broad features of the initial photon fluxes. The differential cross-sections show systematic differences from these predictions which are more pronounced at high |yee | and |cos θ * | values. [Figure not available: see fulltext.].
Published: 2023

15. Search for flavour-changing neutral current interactions of the top quark and the Higgs boson in events with a pair of τ-leptons in pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, and Arena, E
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Flavour Changing Neutral Currents, Hadron-Hadron Scattering, Higgs Physics, Top Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for flavour-changing neutral current (FCNC) tqH interactions involving a top quark, another up-type quark (q = u, c), and a Standard Model (SM) Higgs boson decaying into a τ-lepton pair (H → τ + τ −) is presented. The search is based on a dataset of pp collisions at s = 13 TeV that corresponds to an integrated luminosity of 139 fb −1 recorded with the ATLAS detector at the Large Hadron Collider. Two processes are considered: single top quark FCNC production in association with a Higgs boson (pp → tH), and top quark pair production in which one of top quarks decays into Wb and the other decays into qH through the FCNC interactions. The search selects events with two hadronically decaying τ-lepton candidates (τ had) or at least one τ had with an additional lepton (e, μ), as well as multiple jets. Event kinematics is used to separate signal from the background through a multivariate discriminant. A slight excess of data is observed with a significance of 2.3σ above the expected SM background, and 95% CL upper limits on the t → qH branching ratios are derived. The observed (expected) 95% CL upper limits set on the t → cH and t → uH branching ratios are 9.4×10−4(4.8−1.4+2.2×10−4) and 6.9×10−4(3.5−1.0+1.5×10−4) , respectively. The corresponding combined observed (expected) upper limits on the dimension-6 operator Wilson coefficients in the effective tqH couplings are Ccϕ < 1.35 (0.97) and Cuϕ < 1.16 (0.82). [Figure not available: see fulltext.]
Published: 2023

16. Search for resonant and non-resonant Higgs boson pair production in the bb¯τ+τ− decay channel using 13 TeV pp collision data from the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Arcangeletti, C
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Higgs Physics, Hadron-Hadron Scattering, Proton-Proton Scattering, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for Higgs boson pair production in events with two b-jets and two τ-leptons is presented, using a proton–proton collision dataset with an integrated luminosity of 139 fb −1 collected at s = 13 TeV by the ATLAS experiment at the LHC. Higgs boson pairs produced non-resonantly or in the decay of a narrow scalar resonance in the mass range from 251 to 1600 GeV are targeted. Events in which at least one τ-lepton decays hadronically are considered, and multivariate discriminants are used to reject the backgrounds. No significant excess of events above the expected background is observed in the non-resonant search. The largest excess in the resonant search is observed at a resonance mass of 1 TeV, with a local (global) significance of 3.1σ (2.0σ). Observed (expected) 95% confidence-level upper limits are set on the non-resonant Higgs boson pair-production cross-section at 4.7 (3.9) times the Standard Model prediction, assuming Standard Model kinematics, and on the resonant Higgs boson pair-production cross-section at between 21 and 900 fb (12 and 840 fb), depending on the mass of the narrow scalar resonance. [Figure not available: see fulltext.]
Published: 2023

17. Search for high-mass Wγ and Zγ resonances using hadronic W/Z boson decays from 139 fb−1 of pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Arcangeletti, C
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for high-mass charged and neutral bosons decaying to Wγ and Zγ final states is presented in this paper. The analysis uses a data sample of s = 13 TeV proton-proton collisions with an integrated luminosity of 139 fb −1 collected by the ATLAS detector during LHC Run 2 operation. The sensitivity of the search is determined using models of the production and decay of spin-1 charged bosons and spin-0/2 neutral bosons. The range of resonance masses explored extends from 1.0 TeV to 6.8 TeV. At these high resonance masses, it is beneficial to target the hadronic decays of the W and Z bosons because of their large branching fractions. The decay products of the high-momentum W/Z bosons are strongly collimated and boosted-boson tagging techniques are employed to improve the sensitivity. No evidence of a signal above the Standard Model backgrounds is observed, and upper limits on the production cross-sections of these bosons times their branching fractions to Wγ and Zγ are derived for various boson production models. [Figure not available: see fulltext.].
Published: 2023

18. Search for tt¯H/A→tt¯tt¯ production in the multilepton final state in proton–proton collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, Arena, E, and Arguin, J-F
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Beyond Standard Model, Hadron-Hadron Scattering, Top Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for a new heavy scalar or pseudo-scalar Higgs boson (H/A) produced in association with a pair of top quarks, with the Higgs boson decaying into a pair of top quarks (H/A → tt¯) is reported. The search targets a final state with exactly two leptons with same-sign electric charges or at least three leptons. The analysed dataset corresponds to an integrated luminosity of 139 fb −1 of proton–proton collisions collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Two multivariate classifiers are used to separate the signal from the background. No significant excess of events over the Standard Model expectation is observed. The results are interpreted in the context of a type-II two-Higgs-doublet model. The observed (expected) upper limits at 95% confidence level on the tt¯ H/ A production cross-section times the branching ratio of H/A → tt¯ range between 14 (10) fb and 6 (5) fb for a heavy Higgs boson with mass between 400 GeV and 1000 GeV, respectively. Assuming that only one particle, either the scalar H or the pseudo-scalar A, contributes to the tt¯ tt¯ final state, values of tan β below 1.2 or 0.5 are excluded for a mass of 400 GeV or 1000 GeV, respectively. These exclusion ranges increase to tan β below 1.6 or 0.6 when both particles are considered. [Figure not available: see fulltext.]
Published: 2023

19. Search for pair-produced scalar and vector leptoquarks decaying into third-generation quarks and first- or second-generation leptons in pp collisions with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, Arena, E, and Arguin, J-F
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, Exotics, Hadron-Hadron Scattering, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for pair-produced scalar and vector leptoquarks decaying into quarks and leptons of different generations is presented. It uses the full LHC Run 2 (2015–2018) data set of 139 fb−1 collected with the ATLAS detector in proton–proton collisions at a centre-of-mass energy of s = 13 TeV. Scalar leptoquarks with charge −(1/3)e as well as scalar and vector leptoquarks with charge +(2/3)e are considered. All possible decays of the pair-produced leptoquarks into quarks of the third generation (t, b) and charged or neutral leptons of the first or second generation (e, μ, ν) with exactly one electron or muon in the final state are investigated. No significant deviations from the Standard Model expectation are observed. Upper limits on the production cross-section are provided for eight models as a function of the leptoquark mass and the branching ratio of the leptoquark into the charged or neutral lepton. In addition, lower limits on the leptoquark masses are derived for all models across a range of branching ratios. Two of these models have the goal of providing an explanation for the recent B-anomalies. In both models, a vector leptoquark decays into charged and neutral leptons of the second generation with a similar branching fraction. Lower limits of 1980 GeV and 1710 GeV are set on the leptoquark mass for these two models. [Figure not available: see fulltext.]
Published: 2023

20. A search for heavy Higgs bosons decaying into vector bosons in same-sign two-lepton final states in pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aoki, T, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, and Arena, E
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Higgs Physics, Hadron-Hadron Scattering, Proton-Proton Scattering, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for heavy Higgs bosons produced in association with a vector boson and decaying into a pair of vector bosons is performed in final states with two leptons (electrons or muons) of the same electric charge, missing transverse momentum and jets. A data sample of proton–proton collisions at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider between 2015 and 2018 is used. The data correspond to a total integrated luminosity of 139 fb −1. The observed data are in agreement with Standard Model background expectations. The results are interpreted using higher-dimensional operators in an effective field theory. Upper limits on the production cross-section are calculated at 95% confidence level as a function of the heavy Higgs boson’s mass and coupling strengths to vector bosons. Limits are set in the Higgs boson mass range from 300 to 1500 GeV, and depend on the assumed couplings. The highest excluded mass for a heavy Higgs boson with the coupling combinations explored is 900 GeV. Limits on coupling strengths are also provided. [Figure not available: see fulltext.]
Published: 2023

21. Search for a new scalar resonance in flavour-changing neutral-current top-quark decays t → qX (q = u, c), with X →bb¯, in proton-proton collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aoki, T, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, and Arena, E
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, Hadron-Hadron Scattering, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for flavour-changing neutral-current decays of a top quark into an up-type quark (either up or charm) and a light scalar particle X decaying into a bottom anti-bottom quark pair is presented. The search focuses on top-quark pair production where one top quark decays to qX, with X → bb¯ , and the other top quark decays according to the Standard Model, with the W boson decaying leptonically. The final state is thus characterised by an isolated electron or muon and at least four jets. Events are categorised according to the multiplicity of jets and jets tagged as originating from b-quarks, and a neural network is used to discriminate between signal and background processes. The data analysed correspond to 139 fb −1 of proton–proton collisions at a centre-of-mass energy of 13 TeV, recorded with the ATLAS detector at the LHC. The 95% confidence-level upper limits between 0.019% and 0.062% are derived for the branching fraction B (t → uX) and between 0.018% and 0.078% for the branching fraction B (t → cX), for masses of the scalar particle X between 20 and 160 GeV. [Figure not available: see fulltext.]
Published: 2023

22. Search for a light charged Higgs boson in t → H±b decays, with H± → cb, in the lepton+jets final state in proton-proton collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Arcangeletti, C
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for a charged Higgs boson, H ±, produced in top-quark decays, t → H ± b, is presented. The search targets H ± decays into a bottom and a charm quark, H ± → cb. The analysis focuses on a selection enriched in top-quark pair production, where one top quark decays into a leptonically decaying W boson and a bottom quark, and the other top quark decays into a charged Higgs boson and a bottom quark. This topology leads to a lepton-plus-jets final state, characterised by an isolated electron or muon and at least four jets. The search exploits the high multiplicity of jets containing b-hadrons, and deploys a neural network classifier that uses the kinematic differences between the signal and the background. The search uses a dataset of proton-proton collisions collected at a centre-of-mass energy s = 13 TeV between 2015 and 2018 with the ATLAS detector at CERN’s Large Hadron Collider, amounting to an integrated luminosity of 139 fb −1. Observed (expected) 95% confidence-level upper limits between 0.15% (0.09%) and 0.42% (0.25%) are derived for the product of branching fractions B (t → H ± b) × B(H ± → cb) for charged Higgs boson masses between 60 and 160 GeV, assuming the SM production of the top-quark pairs. [Figure not available: see fulltext.].
Published: 2023

23. Observation of WWW Production in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector.

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, and Arce, ATH
Subjects: ATLAS Collaboration, Mathematical Sciences, Physical Sciences, Engineering, General Physics
Abstract: This Letter reports the observation of WWW production and a measurement of its cross section using 139 fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. Events with two same-sign leptons (electrons or muons) and at least two jets, as well as events with three charged leptons, are selected. A multivariate technique is then used to discriminate between signal and background events. Events from WWW production are observed with a significance of 8.0 standard deviations, where the expectation is 5.4 standard deviations. The inclusive WWW production cross section is measured to be 820±100 (stat)±80 (syst) fb, approximately 2.6 standard deviations from the predicted cross section of 511±18 fb calculated at next-to-leading-order QCD and leading-order electroweak accuracy.
Published: 2022

24. Search for events with a pair of displaced vertices from long-lived neutral particles decaying into hadronic jets in the ATLAS muon spectrometer in pp collisions at s =13 TeV

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Arcangeletti, C
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Astronomical sciences, Particle and high energy physics
Abstract: A search for events with two displaced vertices from long-lived particle (LLP) pairs using data collected by the ATLAS detector at the LHC is presented. This analysis uses 139 fb-1 of proton-proton collision data at s=13 TeV recorded in 2015-2018. The search employs techniques for reconstructing vertices of LLPs decaying to jets in the muon spectrometer displaced between 3 and 14 m with respect to the primary interaction vertex. The observed numbers of events are consistent with the expected background and limits for several benchmark signals are determined. For the Higgs boson with a mass of 125 GeV, the paper reports the first exclusion limits for branching fractions into neutral long-lived particles below 0.1%, while branching fractions above 10% are excluded at 95% confidence level for LLP proper lifetimes ranging from 4 cm to 72.4 m. In addition, the paper present the first results for the decay of LLPs into tt¯ in the ATLAS muon spectrometer.
Published: 2022

25. Two-particle Bose–Einstein correlations in pp collisions at s=13 TeV measured with the ATLAS detector at the LHC

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adachi, S, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Khoury, K Al, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexandre, D, Alexopoulos, T, Alfonsi, A, Alhroob, M, Ali, B, Alimonti, G, Alison, J, Alkire, SP, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, AA, Alvarez Estevez, M, Álvarez Piqueras, D, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, CF, Anders, JK, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aperio Bella, L, Arabidze, G, Araque, JP, Araujo Ferraz, V, and Araujo Pereira, R
Subjects: Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics
Abstract: This paper presents studies of Bose–Einstein correlations (BEC) in proton–proton collisions at a centre-of-mass energy of 13 TeV, using data from the ATLAS detector at the CERN Large Hadron Collider. Data were collected in a special low-luminosity configuration with a minimum-bias trigger and a high-multiplicity track trigger, accumulating integrated luminosities of 151 μ b- 1 and 8.4 nb- 1, respectively. The BEC are measured for pairs of like-sign charged particles, each with | η| < 2.5 , for two kinematic ranges: the first with particle pT> 100 MeV and the second with particle pT> 500 MeV. The BEC parameters, characterizing the source radius and particle correlation strength, are investigated as functions of charged-particle multiplicity (up to 300) and average transverse momentum of the pair (up to 1.5 GeV). The double-differential dependence on charged-particle multiplicity and average transverse momentum of the pair is also studied. The BEC radius is found to be independent of the charged-particle multiplicity for high charged-particle multiplicity (above 100), confirming a previous observation at lower energy. This saturation occurs independent of the transverse momentum of the pair.
Published: 2022

26. Search for long-lived charginos based on a disappearing-track signature using 136 fb-1 of pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, Arena, E, Arguin, J-F, Argyropoulos, S, and Arling, J-H
Subjects: Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics
Abstract: A search for long-lived charginos produced either directly or in the cascade decay of heavy prompt gluino states is presented. The search is based on proton–proton collision data collected at a centre-of-mass energy of s = 13 TeV between 2015 and 2018 with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 136 fb- 1. Long-lived charginos are characterised by a distinct signature of a short and then disappearing track, and are reconstructed using at least four measurements in the ATLAS pixel detector, with no subsequent measurements in the silicon-microstrip tracking volume nor any associated energy deposits in the calorimeter. The final state is complemented by a large missing transverse-momentum requirement for triggering purposes and at least one high-transverse-momentum jet. No excess above the expected backgrounds is observed. Exclusion limits are set at 95% confidence level on the masses of the chargino and gluino for different chargino lifetimes. Chargino masses up to 660 (210) GeV are excluded in scenarios where the chargino is a pure wino (higgsino). For charginos produced during the cascade decay of a heavy gluino, gluinos with masses below 2.1 TeV are excluded for a chargino mass of 300 GeV and a lifetime of 0.2 ns.
Published: 2022

27. Search for flavour-changing neutral-current interactions of a top quark and a gluon in pp collisions at s=13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Arcangeletti, C
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: A search is presented for the production of a single top quark via left-handed flavour-changing neutral-current (FCNC) interactions of a top quark, a gluon and an up or charm quark. Two production processes are considered: u+ g→ t and c+ g→ t. The analysis is based on proton–proton collision data taken at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. The data set corresponds to an integrated luminosity of 139 fb- 1. Events with exactly one electron or muon, exactly one b-tagged jet and missing transverse momentum are selected, resembling the decay products of a singly produced top quark. Neural networks based on kinematic variables differentiate between events from the two signal processes and events from background processes. The measured data are consistent with the background-only hypothesis, and limits are set on the production cross-sections of the signal processes: σ(u+g→t)×B(t→Wb)×B(W→ℓν)
Published: 2022

28. Search for Higgs bosons decaying into new spin-0 or spin-1 particles in four-lepton final states with the ATLAS detector with 139 fb−1 of pp collision data at s = 13 TeV

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Arcangeletti, C
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Beyond Standard Model, Hadron-Hadron Scattering, Higgs Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: Searches are conducted for new spin-0 or spin-1 bosons using events where a Higgs boson with mass 125 GeV decays into four leptons (ℓ = e, μ). This decay is presumed to occur via an intermediate state which contains two on-shell, promptly decaying bosons: H → XX/ZX → 4ℓ, where the new boson X has a mass between 1 and 60 GeV. The search uses pp collision data collected with the ATLAS detector at the LHC with an integrated luminosity of 139 fb−1 at a centre-of-mass energy s = 13 TeV. The data are found to be consistent with Standard Model expectations. Limits are set on fiducial cross sections and on the branching ratio of the Higgs boson to decay into XX/ZX, improving those from previous publications by a factor between two and four. Limits are also set on mixing parameters relevant in extensions of the Standard Model containing a dark sector where X is interpreted to be a dark boson. [Figure not available: see fulltext.]
Published: 2022

29. Measurement of the polarisation of single top quarks and antiquarks produced in the t-channel at s = 13 TeV and bounds on the tWb dipole operator from the ATLAS experiment

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, Arena, E, and Arguin, J-F
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, Top Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A simultaneous measurement of the three components of the top-quark and top-antiquark polarisation vectors in t-channel single-top-quark production is presented. This analysis is based on data from proton–proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 139 fb−1, collected with the ATLAS detector at the LHC. Selected events contain exactly one isolated electron or muon, large missing transverse momentum and exactly two jets, one being b-tagged. Stringent selection requirements are applied to discriminate t-channel single-top-quark events from the background contributions. The top-quark and top-antiquark polarisation vectors are measured from the distributions of the direction cosines of the charged-lepton momentum in the top-quark rest frame. The three components of the polarisation vector for the selected top-quark event sample are Px′ = 0.01 ± 0.18, Py′ = −0.029 ± 0.027, Pz′ = 0.91 ± 0.10 and for the top-antiquark event sample they are Px′ = −0.02 ± 0.20, Py′ = −0.007 ± 0.051, Pz′ = 0.79 ± 0.16. Normalised differential cross-sections corrected to a fiducial region at the stable-particle level are presented as a function of the charged-lepton angles for top-quark and top-antiquark events inclusively and separately. These measurements are in agreement with Standard Model predictions. The angular differential cross-sections are used to derive bounds on the complex Wilson coefficient of the dimension-six OtW operator in the framework of an effective field theory. The obtained bounds are CtW ∈ [−0.9, 1.4] and CitW ∈ [−0.8, 0.2], both at 95% confidence level. [Figure not available: see fulltext.].
Published: 2022

30. Search for type-III seesaw heavy leptons in leptonic final states in pp collisions at s=13TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, Arena, E, and Arguin, J-F
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: A search for the pair production of heavy leptons as predicted by the type-III seesaw mechanism is presented. The search uses proton–proton collision data at a centre-of-mass energy of 13 TeV, corresponding to 139fb-1 of integrated luminosity recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. The analysis focuses on final states with three or four electrons or muons from the possible decays of new heavy leptons via intermediate electroweak bosons. No significant deviations above the Standard Model expectation are observed; upper and lower limits on the heavy lepton production cross-section and masses are derived respectively. These results are then combined for the first time with the ones already published by ATLAS using the channel with two leptons in the final state. The observed lower limit on the mass of the type-III seesaw heavy leptons combining two, three and four lepton channels together is 910 GeV at the 95% confidence level.
Published: 2022

31. Study of Bc+→J/ψDs+ and Bc+→J/ψDs∗+ decays in pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Arcangeletti, C
Subjects: Mathematical Physics, Particle and High Energy Physics, Mathematical Sciences, Physical Sciences, B Physics, Hadron-Hadron Scattering, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A study of Bc+→J/ψDs+ and Bc+→J/ψDs∗+ decays using 139 fb−1 of integrated luminosity collected with the ATLAS detector from s = 13 TeV pp collisions at the LHC is presented. The ratios of the branching fractions of the two decays to the branching fraction of the Bc+→ J/ψπ+ decay are measured: B(Bc+→J/ψDs+)/B(Bc+→J/ψπ+) = 2.76 ± 0.47 and B(Bc+→J/ψDs∗+)/B(Bc+→J/ψπ+) = 5.33 ± 0.96. The ratio of the branching fractions of the two decays is found to be B(Bc+→J/ψDs∗+)/B(Bc+→J/ψDs∗+) = 1.93 ± 0.26. For the Bc+→J/ψDs∗+ decay, the transverse polarization fraction, Γ±±/Γ, is measured to be 0.70 ± 0.11. The reported uncertainties include both the statistical and systematic components added in quadrature. The precision of the measurements exceeds that in all previous studies of these decays. These results supersede those obtained in the earlier ATLAS study of the same decays with s = 7 and 8 TeV pp collision data. A comparison with available theoretical predictions for the measured quantities is presented. [Figure not available: see fulltext.].
Published: 2022

32. Modelling and computational improvements to the simulation of single vector-boson plus jet processes for the ATLAS experiment

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, and Arce, ATH
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: This paper presents updated Monte Carlo configurations used to model the production of single electroweak vector bosons (W, Z/γ∗) in association with jets in proton-proton collisions for the ATLAS experiment at the Large Hadron Collider. Improvements pertaining to the electroweak input scheme, parton-shower splitting kernels and scale-setting scheme are shown for multi-jet merged configurations accurate to next-to-leading order in the strong and electroweak couplings. The computational resources required for these set-ups are assessed, and approximations are introduced resulting in a factor three reduction of the per-event CPU time without affecting the physics modelling performance. Continuous statistical enhancement techniques are introduced by ATLAS in order to populate low cross-section regions of phase space and are shown to match or exceed the generated effective luminosity. This, together with the lower per-event CPU time, results in a 50% reduction in the required computing resources compared to a legacy set-up previously used by the ATLAS collaboration. The set-ups described in this paper will be used for future ATLAS analyses and lay the foundation for the next generation of Monte Carlo predictions for single vector-boson plus jets production. [Figure not available: see fulltext.].
Published: 2022

33. Search for invisible Higgs-boson decays in events with vector-boson fusion signatures using 139 fb−1 of proton-proton data recorded by the ATLAS experiment

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, and Arce, ATH
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, Higgs Physics, Vector Boson Production, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A direct search for Higgs bosons produced via vector-boson fusion and subsequently decaying into invisible particles is reported. The analysis uses 139 fb−1 of pp collision data at a centre-of-mass energy of s = 13 TeV recorded by the ATLAS detector at the LHC. The observed numbers of events are found to be in agreement with the background expectation from Standard Model processes. For a scalar Higgs boson with a mass of 125 GeV and a Standard Model production cross section, an observed upper limit of 0.145 is placed on the branching fraction of its decay into invisible particles at 95% confidence level, with an expected limit of 0.103. These results are interpreted in the context of models where the Higgs boson acts as a portal to dark matter, and limits are set on the scattering cross section of weakly interacting massive particles and nucleons. Invisible decays of additional scalar bosons with masses from 50 GeV to 2 TeV are also studied, and the derived upper limits on the cross section times branching fraction decrease with increasing mass from 1.0 pb for a scalar boson mass of 50 GeV to 0.1 pb at a mass of 2 TeV. [Figure not available: see fulltext.]
Published: 2022

34. Measurements of the Higgs boson inclusive and differential fiducial cross-sections in the diphoton decay channel with pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Arcangeletti, C
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, Higgs Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A measurement of inclusive and differential fiducial cross-sections for the production of the Higgs boson decaying into two photons is performed using 139 fb−1 of proton-proton collision data recorded at s = 13 TeV by the ATLAS experiment at the Large Hadron Collider. The inclusive cross-section times branching ratio, in a fiducial region closely matching the experimental selection, is measured to be 67 ± 6 fb, which is in agreement with the state-of-the-art Standard Model prediction of 64 ± 4 fb. Extrapolating this result to the full phase space and correcting for the branching ratio, the total cross-section for Higgs boson production is estimated to be 58 ± 6 pb. In addition, the cross-sections in four fiducial regions sensitive to various Higgs boson production modes and differential cross-sections as a function of either one or two of several observables are measured. All the measurements are found to be in agreement with the Standard Model predictions. The measured transverse momentum distribution of the Higgs boson is used as an indirect probe of the Yukawa coupling of the Higgs boson to the bottom and charm quarks. In addition, five differential cross-section measurements are used to constrain anomalous Higgs boson couplings to vector bosons in the Standard Model effective field theory framework. [Figure not available: see fulltext.]
Published: 2022

35. Measurements of Higgs boson production cross-sections in the H → τ+τ− decay channel in pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Arcangeletti, C
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, Higgs Physics, Tau Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: Measurements of the production cross-sections of the Standard Model (SM) Higgs boson (H) decaying into a pair of τ-leptons are presented. The measurements use data collected with the ATLAS detector from pp collisions produced at the Large Hadron Collider at a centre-of-mass energy of s = 13 TeV, corresponding to an integrated luminosity of 139 fb−1. Leptonic (τ → ℓνℓντ) and hadronic (τ → hadrons ντ) decays of the τ-lepton are considered. All measurements account for the branching ratio of H → ττ and are performed with a requirement |yH| < 2.5, where yH is the true Higgs boson rapidity. The cross-section of the pp → H → ττ process is measured to be 2.94 ±0.21(stat)−0.32+0.37(syst) pb, in agreement with the SM prediction of 3.17 ± 0.09 pb. Inclusive cross-sections are determined separately for the four dominant production modes: 2.65 ±0.41(stat)−0.67+0.91(syst) pb for gluon-gluon fusion, 0.197 ±0.028(stat)−0.026+0.032(syst) pb for vector-boson fusion, 0.115 ±0.058(stat)−0.040+0.042(syst) pb for vector-boson associated production, and 0.033 ±0.031(stat)−0.017+0.022(syst) pb for top-quark pair associated production. Measurements in exclusive regions of the phase space, using the simplified template cross-section framework, are also performed. All results are in agreement with the SM predictions. [Figure not available: see fulltext.]
Published: 2022

36. Search for exotic decays of the Higgs boson into bb¯ and missing transverse momentum in pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, Arena, E, and Arguin, J-F
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron scattering, Supersymmetry, Beyond Standard Model, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for the exotic decay of the Higgs boson (H) into a bb¯ resonance plus missing transverse momentum is described. The search is performed with the ATLAS detector at the Large Hadron Collider using 139 fb−1 of pp collisions at s = 13 TeV. The search targets events from ZH production in an NMSSM scenario where H → χ~20χ~10, with χ~20→aχ~10, where a is a light pseudoscalar Higgs boson and χ~1,20 are the two lightest neutralinos. The decay of the a boson into a pair of b-quarks results in a peak in the dijet invariant mass distribution. The final-state signature consists of two leptons, two or more jets, at least one of which is identified as originating from a b-quark, and missing transverse momentum. Observations are consistent with Standard Model expectations and upper limits are set on the product of cross section times branching ratio for a three-dimensional scan of the masses of the χ~20, χ~10 and a boson. [Figure not available: see fulltext.]
Published: 2022

37. Measurements of differential cross-sections in top-quark pair events with a high transverse momentum top quark and limits on beyond the Standard Model contributions to top-quark pair production with the ATLAS detector at s = 13 TeV

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, and Arce, ATH
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, Top Physics, Beyond Standard Model, Hadron-Hadron Scattering, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: Cross-section measurements of top-quark pair production where the hadronically decaying top quark has transverse momentum greater than 355 GeV and the other top quark decays into ℓνb are presented using 139 fb−1 of data collected by the ATLAS experiment during proton-proton collisions at the LHC. The fiducial cross-section at s = 13 TeV is measured to be σ = 1.267 ± 0.005 ± 0.053 pb, where the uncertainties reflect the limited number of data events and the systematic uncertainties, giving a total uncertainty of 4.2%. The cross-section is measured differentially as a function of variables characterising the tt¯ system and additional radiation in the events. The results are compared with various Monte Carlo generators, including comparisons where the generators are reweighted to match a parton-level calculation at next-to-next-to-leading order. The reweighting improves the agreement between data and theory. The measured distribution of the top-quark transverse momentum is used to search for new physics in the context of the effective field theory framework. No significant deviation from the Standard Model is observed and limits are set on the Wilson coefficients of the dimension-six operators OtG and Otq(8), where the limits on the latter are the most stringent to date. [Figure not available: see fulltext.].
Published: 2022

38. Measurement of Higgs boson decay into b-quarks in associated production with a top-quark pair in pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Arcangeletti, C
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: The associated production of a Higgs boson and a top-quark pair is measured in events characterised by the presence of one or two electrons or muons. The Higgs boson decay into a b-quark pair is used. The analysed data, corresponding to an integrated luminosity of 139 fb−1, were collected in proton-proton collisions at the Large Hadron Collider between 2015 and 2018 at a centre-of-mass energy of s = 13 TeV. The measured signal strength, defined as the ratio of the measured signal yield to that predicted by the Standard Model, is 0.35−0.34+0.36. This result is compatible with the Standard Model prediction and corresponds to an observed (expected) significance of 1.0 (2.7) standard deviations. The signal strength is also measured differentially in bins of the Higgs boson transverse momentum in the simplified template cross-section framework, including a bin for specially selected boosted Higgs bosons with transverse momentum above 300 GeV. [Figure not available: see fulltext.]
Published: 2022

39. Search for neutral long-lived particles in pp collisions at s = 13 TeV that decay into displaced hadronic jets in the ATLAS calorimeter

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Appelt, C, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, and Arce, ATH
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for decays of pair-produced neutral long-lived particles (LLPs) is presented using 139 fb−1 of proton-proton collision data collected by the ATLAS detector at the LHC in 2015–2018 at a centre-of-mass energy of 13 TeV. Dedicated techniques were developed for the reconstruction of displaced jets produced by LLPs decaying hadronically in the ATLAS hadronic calorimeter. Two search regions are defined for different LLP kinematic regimes. The observed numbers of events are consistent with the expected background, and limits for several benchmark signals are determined. For a SM Higgs boson with a mass of 125 GeV, branching ratios above 10% are excluded at 95% confidence level for values of c times LLP mean proper lifetime in the range between 20 mm and 10 m depending on the model. Upper limits are also set on the cross-section times branching ratio for scalars with a mass of 60 GeV and for masses between 200 GeV and 1 TeV. [Figure not available: see fulltext.]
Published: 2022

40. Erratum to: Search for single top-quark production via flavour-changing neutral currents at 8 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Agricola, J, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, and Artamonov, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: One correction is noted for the paper. The branching fraction (Formula presented.) was not included in the conversion of the observed cross-section limit, (Formula presented.) to the coupling constants κugt and κcgt and the branching fractions B(t → ug) and B(t → cg). The inclusion leads to weaker observed exclusion limits on the coupling constants divided by the scale of new physics of (Formula presented.) and (Formula presented.) and on the branching fractions B(t → ug) < 1.2×10−4 and B(t → cg) < 6.4×10−4. The predicted exclusion limits on the coupling constants divided by the scale of newphysics are (Formula presented.) and (Formula presented.) and on the branching fractions B(t → ug) < 1.1 × 10−4 and B(t → cg) < 5.7 × 10−4. Updated distributions of the observed upper limits on the coupling constants for combinations of cgt and ugt channels are shown in Figure 10a and on the branching fractions in Figure 10b.
Published: 2022

41. Configuration and performance of the ATLAS b-jet triggers in Run 2

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Alison, J, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Pereira, R Araujo, Arcangeletti, C, and Arce, ATH
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: Several improvements to the ATLAS triggers used to identify jets containing b-hadrons (b-jets) were implemented for data-taking during Run 2 of the Large Hadron Collider from 2016 to 2018. These changes include reconfiguring the b-jet trigger software to improve primary-vertex finding and allow more stable running in conditions with high pile-up, and the implementation of the functionality needed to run sophisticated taggers used by the offline reconstruction in an online environment. These improvements yielded an order of magnitude better light-flavour jet rejection for the same b-jet identification efficiency compared to the performance in Run 1 (2011–2012). The efficiency to identify b-jets in the trigger, and the conditional efficiency for b-jets that satisfy offline b-tagging requirements to pass the trigger are also measured. Correction factors are derived to calibrate the b-tagging efficiency in simulation to match that observed in data. The associated systematic uncertainties are substantially smaller than in previous measurements. In addition, b-jet triggers were operated for the first time during heavy-ion data-taking, using dedicated triggers that were developed to identify semileptonic b-hadron decays by selecting events with geometrically overlapping muons and jets.
Published: 2021

42. Measurement of b-quark fragmentation properties in jets using the decay B±→ J/ψK± in pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, Arena, E, Arguin, J-F, and Argyropoulos, S
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, Hadron-Hadron scattering, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: The fragmentation properties of jets containing b-hadrons are studied using charged B mesons in 139 fb−1 of pp collisions at s = 13 TeV, recorded with the ATLAS detector at the LHC during the period from 2015 to 2018. The B mesons are reconstructed using the decay of B± into J/ψK±, with the J/ψ decaying into a pair of muons. Jets are reconstructed using the anti-kt algorithm with radius parameter R = 0.4. The measurement determines the longitudinal and transverse momentum profiles of the reconstructed B hadrons with respect to the axes of the jets to which they are geometrically associated. These distributions are measured in intervals of the jet transverse momentum, ranging from 50 GeV to above 100 GeV. The results are corrected for detector effects and compared with several Monte Carlo predictions using different parton shower and hadronisation models. The results for the longitudinal and transverse profiles provide useful inputs to improve the description of heavy-flavour fragmentation in jets. [Figure not available: see fulltext.].
Published: 2021

43. Search for chargino–neutralino pair production in final states with three leptons and missing transverse momentum in s=13 TeV pp collisions with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Khoury, K Al, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, Arena, E, Arguin, J-F, and Argyropoulos, S
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: A search for chargino–neutralino pair production in three-lepton final states with missing transverse momentum is presented. The study is based on a dataset of s=13 TeV pp collisions recorded with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 139 fb - 1. No significant excess relative to the Standard Model predictions is found in data. The results are interpreted in simplified models of supersymmetry, and statistically combined with results from a previous ATLAS search for compressed spectra in two-lepton final states. Various scenarios for the production and decay of charginos (χ~1±) and neutralinos (χ~20) are considered. For pure higgsino χ~1±χ~20 pair-production scenarios, exclusion limits at 95% confidence level are set on χ~20 masses up to 210 GeV. Limits are also set for pure wino χ~1±χ~20 pair production, on χ~20 masses up to 640 GeV for decays via on-shell W and Z bosons, up to 300 GeV for decays via off-shell W and Z bosons, and up to 190 GeV for decays via W and Standard Model Higgs bosons.
Published: 2021

44. Erratum to: Measurement of hadronic event shapes in high-pT multijet final states at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Araujo Pereira, R
Subjects: Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics
Abstract: An error in the normalization of the Aplanarity and D-parameter has been found. Insufficient precision on the eigenvalue calculation can cause λ3 to be negative, exclusively in two-jet events, yielding an underestimation of the inclusive two-jet cross section.
Published: 2021

45. Measurement of angular and momentum distributions of charged particles within and around jets in Pb+Pb and pp collisions at sNN=5.02 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adachi, S, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexandre, D, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Alimonti, G, Alison, J, Alkire, SP, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, AA, Alvarez Estevez, M, Álvarez Piqueras, D, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, CF, Anders, JK, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aperio Bella, L, Arabidze, G, Araque, JP, and Araujo Ferraz, V
Published: 2021

46. Search for heavy long-lived multicharged particles in proton-proton collisions at s=13 TeV using the ATLAS detector

Author: Aaboud, M, Aad, G, Abbott, B, Abbott, DC, Abdinov, O, Abeloos, B, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Adachi, S, Adam, L, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adye, T, Affolder, AA, Afik, Y, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexandre, D, Alexopoulos, T, Alhroob, M, Ali, B, Alimonti, G, Alison, J, Alkire, SP, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, AA, Alstaty, MI, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angelozzi, I, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aperio Bella, L, Arabidze, G, Araque, JP, Araujo Ferraz, V, Araujo Pereira, R, Arce, ATH, Ardell, RE, and Arduh, FA
Published: 2021

47. Erratum to: Measurement of light-by-light scattering and search for axion-like particles with 2.2 nb−1 of Pb+Pb data with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Araujo Pereira, R
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: One correction is noted for the paper, which does not affect the results reported. The right panel of figure 9 is corrected as it contained the “internal” label, giving the misleading impression on the credibility of the figure.
Published: 2021

48. Measurement of the tt¯tt¯ production cross section in pp collisions at s = 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, Arena, E, Arguin, J-F, Argyropoulos, S, and Arling, J-H
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron scattering, Top physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A measurement of four-top-quark production using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS detector at the Large Hadron Collider corresponding to an integrated luminosity of 139 fb−1 is presented. Events are selected if they contain a single lepton (electron or muon) or an opposite-sign lepton pair, in association with multiple jets. The events are categorised according to the number of jets and how likely these are to contain b-hadrons. A multivariate technique is then used to discriminate between signal and background events. The measured four-top-quark production cross section is found to be 26−15+17 fb, with a corresponding observed (expected) significance of 1.9 (1.0) standard deviations over the background-only hypothesis. The result is combined with the previous measurement performed by the ATLAS Collaboration in the multilepton final state. The combined four-top-quark production cross section is measured to be 24−6+7 fb, with a corresponding observed (expected) signal significance of 4.7 (2.6) standard deviations over the background-only predictions. It is consistent within 2.0 standard deviations with the Standard Model expectation of 12.0 ± 2.4 fb. [Figure not available: see fulltext.].
Published: 2021

49. Search for exotic decays of the Higgs boson into long-lived particles in pp collisions at s = 13 TeV using displaced vertices in the ATLAS inner detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, Arena, E, Arguin, J-F, Argyropoulos, S, and Arling, J-H
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Exotics, Hadron-Hadron scattering, Higgs physics, proton-proton scattering, Lifetime, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A novel search for exotic decays of the Higgs boson into pairs of long-lived neutral particles, each decaying into a bottom quark pair, is performed using 139 fb−1 of s = 13 TeV proton-proton collision data collected with the ATLAS detector at the LHC. Events consistent with the production of a Higgs boson in association with a leptonically decaying Z boson are analysed. Long-lived particle (LLP) decays are reconstructed from inner-detector tracks as displaced vertices with high mass and track multiplicity relative to Standard Model processes. The analysis selection requires the presence of at least two displaced vertices, effectively suppressing Standard Model backgrounds. The residual background contribution is estimated using a data-driven technique. No excess over Standard Model predictions is observed, and upper limits are set on the branching ratio of the Higgs boson to LLPs. Branching ratios above 10% are excluded at 95% confidence level for LLP mean proper lifetimes cτ as small as 4 mm and as large as 100 mm. For LLP masses below 40 GeV, these results represent the most stringent constraint in this lifetime regime. [Figure not available: see fulltext.]
Published: 2021

50. Measurement of the production cross section of pairs of isolated photons in pp collisions at 13 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Arcangeletti, C, Arce, ATH, Arena, E, Arguin, J-F, and Argyropoulos, S
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, Hadron-Hadron scattering, photon production, proton-proton scattering, QCD, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A measurement of prompt photon-pair production in proton-proton collisions at s = 13 TeV is presented. The data were recorded by the ATLAS detector at the LHC with an integrated luminosity of 139 fb−1. Events with two photons in the well-instrumented region of the detector are selected. The photons are required to be isolated and have a transverse momentum of pT,γ1(2)> 40 (30) GeV for the leading (sub-leading) photon. The differential cross sections as functions of several observables for the diphoton system are measured and compared with theoretical predictions from state-of-the-art Monte Carlo and fixed-order calculations. The QCD predictions from next-to-next-to-leading-order calculations and multi-leg merged calculations are able to describe the measured integrated and differential cross sections within uncertainties, whereas lower-order calculations show significant deviations, demonstrating that higher-order perturbative QCD corrections are crucial for this process. The resummed predictions with parton showers additionally provide an excellent description of the low transverse-momentum regime of the diphoton system. [Figure not available: see fulltext.].
Published: 2021

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