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114 results on '"BORDYUZHIN, IG"'

1. Measurements of Proton High-Order Cumulants in sqrt[s_{NN}]=3 GeV Au+Au Collisions and Implications for the QCD Critical Point

Author: Abdallah, MS, Aboona, BE, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball Cap, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Cai, XZ, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dixit, P, Dong, X, Drachenberg, JL, Duckworth, E, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, and Hamed, A
Subjects: STAR Collaboration, General Physics, Engineering, Physical Sciences, Mathematical Sciences
Abstract: We report cumulants of the proton multiplicity distribution from dedicated fixed-target Au+Au collisions at sqrt[s_{NN}]=3.0 GeV, measured by the STAR experiment in the kinematic acceptance of rapidity (y) and transverse momentum (p_{T}) within -0.5
Published: 2022

2. Longitudinal double-spin asymmetry for inclusive jet and dijet production in polarized proton collisions at s=510 GeV

Author: Abdallah, MS, Aboona, BE, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Cap, JG Ball, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dixit, P, Dong, X, Drachenberg, JL, Duckworth, E, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, and Hamed, A
Subjects: Quantum Physics, Particle and Plasma Physics, Molecular, Nuclear, Atomic, Nuclear & Particles Physics, Astronomical and Space Sciences
Abstract: We report measurements of the longitudinal double-spin asymmetry, ALL, for inclusive jet and dijet production in polarized proton-proton collisions at midrapidity and center-of-mass energy s=510 GeV, using the high luminosity data sample collected by the STAR experiment in 2013. These measurements complement and improve the precision of previous STAR measurements at the same center-of-mass energy that probe the polarized gluon distribution function at partonic momentum fraction 0.015≲x≲0.25. The dijet asymmetries are separated into four jet-pair topologies, which provide further constraints on the x dependence of the polarized gluon distribution function. These measurements are in agreement with previous STAR measurements and with predictions from current next-to-leading-order global analyses. They provide more precise data at low dijet invariant mass that will better constrain the shape of the polarized gluon distribution function of the proton.
Published: 2022

3. Differential measurements of jet substructure and partonic energy loss in Au + Au collisions at sNN=200 GeV

Author: Abdallah, MS, Aboona, BE, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Cap, JG Ball, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dixit, P, Dong, X, Drachenberg, JL, Duckworth, E, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, and Hamed, A
Subjects: Particle and Plasma Physics, Molecular, Nuclear, Atomic, Nuclear & Particles Physics
Abstract: The STAR collaboration presents jet substructure measurements related to both the momentum fraction and the opening angle within jets in p+p and Au+Au collisions at sNN =200GeV. The substructure observables include SoftDrop groomed momentum fraction (zg), groomed jet radius (Rg), and subjet momentum fraction (zSJ) and opening angle (θSJ). The latter observable is introduced for the first time. Fully corrected subjet measurements are presented for p+p collisions and are compared to leading-order Monte Carlo models. The subjet θSJ distributions reflect the jets leading opening angle and are utilized as a proxy for the resolution scale of the medium in Au+Au collisions. We compare data from Au+Au collisions to those from p+p which are embedded in minimum-bias Au+Au events in order to include the effects of detector smearing and the heavy-ion collision underlying event. The subjet observables are shown to be more robust to the background than zg and Rg. We observe no significant modifications of the subjet observables within the two highest-energy, back-to-back jets, resulting in a distribution of opening angles and the splittings that are vacuumlike. We also report measurements of the differential dijet momentum imbalance (AJ) for jets of varying θSJ. We find no qualitative differences in energy loss signatures for varying angular scales in the range 0.1< θSJ
Published: 2022

4. Probing the Gluonic Structure of the Deuteron with J/ψ Photoproduction in d+Au Ultraperipheral Collisions

Author: Abdallah, MS, Aboona, BE, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Aitbaev, A, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball Cap, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Cai, XZ, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dixit, P, Dong, X, Drachenberg, JL, Duckworth, E, Dunlop, JC, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamed, A, Han, Y, Harabasz, S, Harasty, MD, and Harris, JW
Subjects: STAR Collaboration, General Physics, Engineering, Physical Sciences, Mathematical Sciences
Abstract: Understanding gluon density distributions and how they are modified in nuclei are among the most important goals in nuclear physics. In recent years, diffractive vector meson production measured in ultraperipheral collisions (UPCs) at heavy-ion colliders has provided a new tool for probing the gluon density. In this Letter, we report the first measurement of J/ψ photoproduction off the deuteron in UPCs at the center-of-mass energy sqrt[s_{NN}]=200 GeV in d+Au collisions. The differential cross section as a function of momentum transfer -t is measured. In addition, data with a neutron tagged in the deuteron-going zero-degree calorimeter is investigated for the first time, which is found to be consistent with the expectation of incoherent diffractive scattering at low momentum transfer. Theoretical predictions based on the color glass condensate saturation model and the leading twist approximation nuclear shadowing model are compared with the data quantitatively. A better agreement with the saturation model has been observed. With the current measurement, the results are found to be directly sensitive to the gluon density distribution of the deuteron and the deuteron breakup process, which provides insights into the nuclear gluonic structure.
Published: 2022

5. Invariant jet mass measurements in pp collisions at s =200 GeV at RHIC

Author: Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Cap, JG Ball, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Han, Y, and Harabasz, S
Subjects: Quantum Physics, Particle and Plasma Physics, Molecular, Nuclear, High Energy Physics::Experiment, Nuclear Experiment, Atomic, Nuclear & Particles Physics, Astronomical and Space Sciences
Abstract: We present the first inclusive measurements of the invariant and softdrop jet mass in proton-proton collisions at s=200 GeV at STAR. The measurements are fully corrected for detector effects, and reported differentially in both the jet transverse momentum and jet radius parameter. We compare the measurements to established leading-order Monte Carlo event generators and find that STAR-tuned pythia-6 reproduces the data, while LHC tunes of pythia-8 and herwig-7 do not agree with the data, providing further constraints on parameter tuning. Finally, we observe that softdrop grooming, for which the contribution of wide-angle nonperturbative radiation is suppressed, shifts the jet mass distributions into closer agreement with the partonic jet mass as determined by both pythia-8 and a next-to-leading-logarithmic accuracy perturbative QCD calculation. These measurements complement recent LHC measurements in a different kinematic region, as well as establish a baseline for future jet mass measurements in heavy-ion collisions at RHIC.
Published: 2021

6. Cumulants and correlation functions of net-proton, proton, and antiproton multiplicity distributions in Au+Au collisions at energies available at the BNL Relativistic Heavy Ion Collider

Author: Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Cap, JG Ball, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Han, Y, and Harabasz, S
Subjects: Particle and Plasma Physics, nucl-th, hep-ex, Molecular, Physics::Accelerator Physics, Nuclear, High Energy Physics::Experiment, hep-ph, Nuclear Experiment, nucl-ex, Atomic, Nuclear & Particles Physics
Abstract: We report a systematic measurement of cumulants, Cn, for net-proton, proton, and antiproton multiplicity distributions, and correlation functions, κn, for proton and antiproton multiplicity distributions up to the fourth order in Au+Au collisions at sNN=7.7, 11.5, 14.5, 19.6, 27, 39, 54.4, 62.4, and 200 GeV. The Cn and κn are presented as a function of collision energy, centrality and kinematic acceptance in rapidity, y, and transverse momentum, pT. The data were taken during the first phase of the Beam Energy Scan (BES) program (2010-2017) at the BNL Relativistic Heavy Ion Collider (RHIC) facility. The measurements are carried out at midrapidity (|y|< 0.5) and transverse momentum 0.4
Published: 2021

7. Azimuthal anisotropy measurements of strange and multistrange hadrons in U+ U collisions at sNN =193 GeV at the BNL Relativistic Heavy Ion Collider

Author: Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball Cap, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Han, Y, and Harabasz, S
Subjects: Nuclear Theory, Nuclear Experiment
Abstract: We present systematic measurements of azimuthal anisotropy for strange and multistrange hadrons (Ks0, Λ, Ξ, and ω) and φ mesons at midrapidity (|y|< 1.0) in collisions of U+U nuclei at sNN=193 GeV, recorded by the STAR detector at the Relativistic Heavy Ion Collider. Transverse momentum (pT) dependence of flow coefficients (v2, v3, and v4) is presented for minimum bias collisions and three different centrality intervals. Number of constituent quark scaling of the measured flow coefficients in U+U collisions is discussed. We also present the ratio of vn scaled by the participant eccentricity (ɛn2) to explore system size dependence and collectivity in U+U collisions. The magnitude of v2/ɛ2 is found to be smaller in U+U collisions than that in central Au+Au collisions contradicting naive eccentricity scaling. Furthermore, the ratios between various flow harmonics (v3/v23/2, v4/v24/2) are studied and compared with hydrodynamic and transport model calculations.
Published: 2021

8. Azimuthal anisotropy measurements of strange and multistrange hadrons in U+U collisions at sNN=193 GeV at the BNL Relativistic Heavy Ion Collider

Author: Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Cap, JG Ball, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Han, Y, and Harabasz, S
Subjects: Particle and Plasma Physics, Nuclear Theory, Molecular, Nuclear, Nuclear Experiment, Atomic, Nuclear & Particles Physics
Abstract: We present systematic measurements of azimuthal anisotropy for strange and multistrange hadrons (Ks0, Λ, Ξ, and ω) and φ mesons at midrapidity (|y|< 1.0) in collisions of U+U nuclei at sNN=193 GeV, recorded by the STAR detector at the Relativistic Heavy Ion Collider. Transverse momentum (pT) dependence of flow coefficients (v2, v3, and v4) is presented for minimum bias collisions and three different centrality intervals. Number of constituent quark scaling of the measured flow coefficients in U+U collisions is discussed. We also present the ratio of vn scaled by the participant eccentricity (ɛn2) to explore system size dependence and collectivity in U+U collisions. The magnitude of v2/ɛ2 is found to be smaller in U+U collisions than that in central Au+Au collisions contradicting naive eccentricity scaling. Furthermore, the ratios between various flow harmonics (v3/v23/2, v4/v24/2) are studied and compared with hydrodynamic and transport model calculations.
Published: 2021

9. Measurement of transverse single-spin asymmetries of π0 and electromagnetic jets at forward rapidity in 200 and 500 GeV transversely polarized proton-proton collisions MEASUREMENT of TRANSVERSE SINGLE-SPIN ASYMMETRIES ⋯ ADAM J. et al

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, and Holub, L
Subjects: hep-ex, High Energy Physics::Experiment, Nuclear Experiment
Abstract: The STAR Collaboration reports measurements of the transverse single-spin asymmetry (TSSA) of inclusive π0 at center-of-mass energies (s) of 200 GeV and 500 GeV in transversely polarized proton-proton collisions in the pseudo-rapidity region 2.7 to 4.0. The results at the two different energies show a continuous increase of the TSSA with Feynman-x, and, when compared to previous measurements, no dependence on s from 19.4 GeV to 500 GeV is found. To investigate the underlying physics leading to this large TSSA, different topologies have been studied. π0 with no nearby particles tend to have a higher TSSA than inclusive π0. The TSSA for inclusive electromagnetic jets, sensitive to the Sivers effect in the initial state, is substantially smaller, but shows the same behavior as the inclusive π0 asymmetry as a function of Feynman-x. To investigate final-state effects, the Collins asymmetry of π0 inside electromagnetic jets has been measured. The Collins asymmetry is analyzed for its dependence on the π0 momentum transverse to the jet thrust axis and its dependence on the fraction of jet energy carried by the π0. The asymmetry was found to be small in each case for both center-of-mass energies. All the measurements are compared to QCD-based theoretical calculations for transverse-momentum-dependent parton distribution functions and fragmentation functions. Some discrepancies are found, which indicates new mechanisms might be involved.
Published: 2021

10. Methods for a blind analysis of isobar data collected by the STAR collaboration

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, MC, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, and Horvat, S
Subjects: Heavy-ion collisions, Chiral magnetic effect, hep-ex, Blind analysis, nucl-ex, Nuclear & Particles Physics
Abstract: In 2018, the STAR collaboration collected data from 4496Ru+4496Ru and 4096Zr+4096Zr at sNN=200 GeV to search for the presence of the chiral magnetic effect in collisions of nuclei. The isobar collision species alternated frequently between 4496Ru+4496Ru and 4096Zr+4096Zr. In order to conduct blind analyses of studies related to the chiral magnetic effect in these isobar data, STAR developed a three-step blind analysis procedure. Analysts are initially provided a “reference sample” of data, comprised of a mix of events from the two species, the order of which respects time-dependent changes in run conditions. After tuning analysis codes and performing time-dependent quality assurance on the reference sample, analysts are provided a species-blind sample suitable for calculating efficiencies and corrections for individual ≈ 30 -min data-taking runs. For this sample, species-specific information is disguised, but individual output files contain data from a single isobar species. Only run-by-run corrections and code alteration subsequent to these corrections are allowed at this stage. Following these modifications, the “frozen” code is passed over the fully un-blind data, completing the blind analysis. As a check of the feasibility of the blind analysis procedure, analysts completed a “mock data challenge,” analyzing data from Au + Au collisions at sNN=27 GeV, collected in 2018. The Au + Au data were prepared in the same manner intended for the isobar blind data. The details of the blind analysis procedure and results from the mock data challenge are presented.
Published: 2021

11. Longitudinal double-spin asymmetry for inclusive jet and dijet production in polarized proton collisions at s=200 GeV

Author: Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Ball Cap, JG, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Han, Y, and Harabasz, S
Subjects: Quantum Physics, Particle and Plasma Physics, hep-ex, Molecular, High Energy Physics::Experiment, Nuclear, Nuclear Experiment, nucl-ex, Atomic, Nuclear & Particles Physics, Astronomical and Space Sciences
Abstract: We report high-precision measurements of the longitudinal double-spin asymmetry, ALL, for midrapidity inclusive jet and dijet production in polarized pp collisions at a center-of-mass energy of s=200 GeV. The new inclusive jet data are sensitive to the gluon helicity distribution, Δg(x,Q2), for gluon momentum fractions in the range from x≃0.05 to x≃0.5, while the new dijet data provide further constraints on the x dependence of Δg(x,Q2). The results are in good agreement with previous measurements at s=200 GeV and with recent theoretical evaluations of prior world data. Our new results have better precision and thus strengthen the evidence that Δg(x,Q2) is positive for x>0.05.
Published: 2021

12. Measurement of transverse single-spin asymmetries of π0 and electromagnetic jets at forward rapidity in 200 and 500 GeV transversely polarized proton-proton collisions

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, and Holub, L
Subjects: Quantum Physics, Particle and Plasma Physics, hep-ex, Molecular, High Energy Physics::Experiment, Nuclear, Nuclear Experiment, Atomic, Nuclear & Particles Physics, Astronomical and Space Sciences
Abstract: The STAR Collaboration reports measurements of the transverse single-spin asymmetry (TSSA) of inclusive π0 at center-of-mass energies (s) of 200 GeV and 500 GeV in transversely polarized proton-proton collisions in the pseudo-rapidity region 2.7 to 4.0. The results at the two different energies show a continuous increase of the TSSA with Feynman-x, and, when compared to previous measurements, no dependence on s from 19.4 GeV to 500 GeV is found. To investigate the underlying physics leading to this large TSSA, different topologies have been studied. π0 with no nearby particles tend to have a higher TSSA than inclusive π0. The TSSA for inclusive electromagnetic jets, sensitive to the Sivers effect in the initial state, is substantially smaller, but shows the same behavior as the inclusive π0 asymmetry as a function of Feynman-x. To investigate final-state effects, the Collins asymmetry of π0 inside electromagnetic jets has been measured. The Collins asymmetry is analyzed for its dependence on the π0 momentum transverse to the jet thrust axis and its dependence on the fraction of jet energy carried by the π0. The asymmetry was found to be small in each case for both center-of-mass energies. All the measurements are compared to QCD-based theoretical calculations for transverse-momentum-dependent parton distribution functions and fragmentation functions. Some discrepancies are found, which indicates new mechanisms might be involved.
Published: 2021

13. Comparison of transverse single-spin asymmetries for forward π0 production in polarized pp, pAl and pAu collisions at nucleon pair c.m. energy sNN =200 GeV

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, and Hong, Y
Subjects: Quantum Physics, Particle and Plasma Physics, hep-ex, Nuclear Theory, Molecular, Nuclear, High Energy Physics::Experiment, Nuclear Experiment, nucl-ex, Atomic, Nuclear & Particles Physics, Astronomical and Space Sciences
Abstract: The STAR collaboration reports a measurement of the transverse single-spin asymmetries, AN, for neutral pions produced in polarized proton collisions with protons (pp), with aluminum nuclei (pAl) and with gold nuclei (pAu) at a nucleon-nucleon center-of-mass energy of 200 GeV. Neutral pions are observed in the forward direction relative to the transversely polarized proton beam, in the pseudorapidity region 2.7
Published: 2021

14. Global Polarization of Ξ and Ω Hyperons in Au+Au Collisions at sqrt[s_{NN}]=200 GeV

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, and Hong, Y
Subjects: STAR Collaboration, General Physics, Engineering, Physical Sciences, nucl-ex, Mathematical Sciences
Abstract: Global polarization of Ξ and Ω hyperons has been measured for the first time in Au+Au collisions at sqrt[s_{NN}]=200 GeV. The measurements of the Ξ^{-} and Ξ[over ¯]^{+} hyperon polarization have been performed by two independent methods, via analysis of the angular distribution of the daughter particles in the parity violating weak decay Ξ→Λ+π, as well as by measuring the polarization of the daughter Λ hyperon, polarized via polarization transfer from its parent. The polarization, obtained by combining the results from the two methods and averaged over Ξ^{-} and Ξ[over ¯]^{+}, is measured to be ⟨P_{Ξ}⟩=0.47±0.10(stat)±0.23(syst)% for the collision centrality 20%-80%. The ⟨P_{Ξ}⟩ is found to be slightly larger than the inclusive Λ polarization and in reasonable agreement with a multiphase transport model. The ⟨P_{Ξ}⟩ is found to follow the centrality dependence of the vorticity predicted in the model, increasing toward more peripheral collisions. The global polarization of Ω, ⟨P_{Ω}⟩=1.11±0.87(stat)±1.97(syst)% was obtained by measuring the polarization of daughter Λ in the decay Ω→Λ+K, assuming the polarization transfer factor C_{ΩΛ}=1.
Published: 2021

15. Flow and interferometry results from Au+Au collisions at sNN =4.5 GeV

Author: Abdallah, MS, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, I, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Baker, W, Cap, JG Ball, Barish, K, Behera, A, Bellwied, R, Bhagat, P, Bhasin, A, Bielcik, J, Bielcikova, J, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bunzarov, I, Butterworth, J, Cai, XZ, Caines, H, de la Barca Sánchez, M Calderón, Campbell, JM, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Dhamija, A, Di Carlo, L, Didenko, L, Dong, X, Drachenberg, JL, Duckworth, E, Dunlop, JC, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fawzi, FM, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Flores, CE, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Gupta, A, Guryn, W, and Hamad, AI
Subjects: Particle and Plasma Physics, Molecular, Nuclear, High Energy Physics::Experiment, Nuclear Experiment, nucl-ex, Atomic, Nuclear & Particles Physics
Abstract: The beam energy scan (BES) program at the BNL Relativistic Heavy Ion Collider (RHIC) was extended to energies below sNN=7.7 GeV in 2015 by successful implementation of the fixed-target mode of operation in the STAR (Solenoidal Tracker At RHIC) experiment. In this mode, ions circulate in one ring of the collider and interact with a stationary target at the entrance of the STAR time projection chamber. The first results for Au+Au collisions at sNN=4.5 GeV are presented, demonstrating good performance of all the relevant detector subsystems in fixed-target mode. Results presented here include directed and elliptic flow of identified hadrons, and radii from pion femtoscopy. The latter, together with recent HADES results, reveal a long-sought peak structure that may be caused by the system evolving through a first-order phase transition from quark-gluon plasma to the hadronic phase. Directed and elliptic flow for pions are presented for the first time at this beam energy. Pion and proton elliptic flow show behavior which hints at constituent quark scaling, and demonstrate that a definitive conclusion will be achievable using the full statistics of the ongoing second phase of BES (BES-II). In particular, BES-II to date has recorded fixed-target data sets with two orders of magnitude more events at each of nine energies between sNN=3.0 and 7.7 GeV.
Published: 2021

16. Nonmonotonic Energy Dependence of Net-Proton Number Fluctuations

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, and Horvat, S
Subjects: STAR Collaboration, General Physics, Engineering, Physical Sciences, Nuclear Experiment, Mathematical Sciences
Abstract: Nonmonotonic variation with collision energy (sqrt[s_{NN}]) of the moments of the net-baryon number distribution in heavy-ion collisions, related to the correlation length and the susceptibilities of the system, is suggested as a signature for the quantum chromodynamics critical point. We report the first evidence of a nonmonotonic variation in the kurtosis times variance of the net-proton number (proxy for net-baryon number) distribution as a function of sqrt[s_{NN}] with 3.1 σ significance for head-on (central) gold-on-gold (Au+Au) collisions measured solenoidal tracker at Relativistic Heavy Ion Collider. Data in noncentral Au+Au collisions and models of heavy-ion collisions without a critical point show a monotonic variation as a function of sqrt[s_{NN}].
Published: 2021

17. Observation of $D_{s}^{\pm}/D^0$ enhancement in Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 200 GeV

Author: Collaboration, STAR, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Sánchez, M Calderón de la Barca, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fu, C, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Ghimire, N, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, and Hoffman, E
Subjects: hep-ex, High Energy Physics::Lattice, High Energy Physics::Phenomenology, Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment
Abstract: We report on the first measurement of charm-strange meson $D_s^{\pm}$ production at midrapidity in Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$ = 200 GeV from the STAR experiment. The yield ratio between strange ($D_{s}^{\pm}$) and non-strange ($D^{0}$) open-charm mesons is presented and compared to model calculations. A significant enhancement, relative to a PYTHIA simulation of $p$+$p$ collisions, is observed in the $D_{s}^{\pm}/D^0$ yield ratio in Au+Au collisions over a large range of collision centralities. Model calculations incorporating abundant strange-quark production in the quark-gluon plasma (QGP) and coalescence hadronization qualitatively reproduce the data. The transverse-momentum integrated yield ratio of $D_{s}^{\pm}/D^0$ at midrapidity is consistent with a prediction from a statistical hadronization model with the parameters constrained by the yields of light and strange hadrons measured at the same collision energy. These results suggest that the coalescence of charm quarks with strange quarks in the QGP plays an important role in $D_{s}^{\pm}$ meson production in heavy-ion collisions.
Published: 2021

18. Measurements of W and Z/γ* cross sections and their ratios in p+p collisions at RHIC

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, J, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Gou, X, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, He, Y, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, and Horvat, S
Subjects: Quantum Physics, Particle and Plasma Physics, hep-ex, Molecular, High Energy Physics::Experiment, Nuclear, nucl-ex, Atomic, Nuclear & Particles Physics, Astronomical and Space Sciences
Abstract: We report on the W and Z/γ∗ differential and total cross sections as well as the W+/W- and (W++W-)/(Z/γ∗) cross section ratios measured by the STAR experiment at RHIC in p+p collisions at s=500 GeV and 510 GeV. The cross sections and their ratios are sensitive to quark and antiquark parton distribution functions. In particular, at leading order, the W cross section ratio is sensitive to the d¯/ū ratio. These measurements were taken at high Q2∼MW2,MZ2 and can serve as input into global analyses to provide constraints on the sea quark distributions. The results presented here combine three STAR datasets from 2011, 2012, and 2013, accumulating an integrated luminosity of 350 pb-1. We also assess the expected impact that our W+/W- cross section ratios will have on various quark distributions, and find sensitivity to the ū-d¯ and d¯/ū distributions.
Published: 2021

19. Measurement of groomed jet substructure observables in p+p collisions at s=200 GeV with STAR

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL
Subjects: hep-ex, Molecular, Astrophysics::Cosmology and Extragalactic Astrophysics, Nuclear & Particles Physics, Atomic, Particle and Plasma Physics, Splitting function, SoftDrop, Groomed jet radius, Nuclear, Nuclear Experiment, Jet substructure, Astrophysics::Galaxy Astrophysics, Mathematical Physics, Astronomical and Space Sciences
Abstract: In this letter, measurements of the shared momentum fraction (zg) and the groomed jet radius (Rg), as defined in the SoftDrop algorithm, are reported in p+p collisions at s=200 GeV collected by the STAR experiment. These substructure observables are differentially measured for jets of varying resolution parameters from R=0.2−0.6 in the transverse momentum range 15
Published: 2020

20. Measurement of groomed jet substructure observables in p+p collisions at s = 200 GeV with STAR

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, and Huang, HZ
Subjects: hep-ex, Molecular, Astrophysics::Cosmology and Extragalactic Astrophysics, Atomic, Nuclear & Particles Physics, Particle and Plasma Physics, Splitting function, SoftDrop, Groomed jet radius, Nuclear, Nuclear Experiment, Jet substructure, Astrophysics::Galaxy Astrophysics, Mathematical Physics, Astronomical and Space Sciences
Abstract: In this letter, measurements of the shared momentum fraction (zg) and the groomed jet radius (Rg), as defined in the SoftDrop algorithm, are reported in p+p collisions at s=200 GeV collected by the STAR experiment. These substructure observables are differentially measured for jets of varying resolution parameters from R=0.2−0.6 in the transverse momentum range 15
Published: 2020

21. Measurement of inclusive charged-particle jet production in Au + Au collisions at sNN=200 GeV

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, and Huang, HZ
Subjects: Particle and Plasma Physics, hep-ex, Astrophysics::High Energy Astrophysical Phenomena, Molecular, High Energy Physics::Experiment, Nuclear, Nuclear Experiment, nucl-ex, Atomic, Nuclear & Particles Physics
Abstract: The STAR Collaboration at the Relativistic Heavy Ion Collider reports the first measurement of inclusive jet production in peripheral and central Au+Au collisions at sNN=200 GeV. Jets are reconstructed with the anti-kT algorithm using charged tracks with pseudorapidity |η
Published: 2020

22. Measurement of inclusive J/ψ polarization in p+p collisions at s=200 GeV by the STAR experiment

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bueltmann, S, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL
Subjects: Quantum Physics, Particle and Plasma Physics, hep-ex, Molecular, Nuclear, nucl-ex, Atomic, Nuclear & Particles Physics, Astronomical and Space Sciences
Abstract: We report on new measurements of inclusive J/ψ polarization at midrapidity in p+p collisions at s=200 GeV by the STAR experiment at the Relativistic Heavy Ion Collider. The polarization parameters, λθ, λφ, and λθφ, are measured as a function of transverse momentum (pT) in both the helicity and Collins-Soper (CS) reference frames within pT
Published: 2020

23. Investigation of the linear and mode-coupled flow harmonics in Au+Au collisions at sNN = 200 GeV

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL
Subjects: Particle and Plasma Physics, Collectivity, Shear viscosity, Molecular, Nuclear, Nuclear Experiment, nucl-ex, Atomic, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Correlation
Abstract: Flow harmonics (vn) of the Fourier expansion for the azimuthal distributions of hadrons are commonly employed to quantify the azimuthal anisotropy of particle production relative to the collision symmetry planes. While lower order Fourier coefficients (v2 and v3) are more directly related to the corresponding eccentricities of the initial state, the higher-order flow harmonics (vn>3) can be induced by a mode-coupled response to the lower-order anisotropies, in addition to a linear response to the same-order anisotropies. These higher-order flow harmonics and their linear and mode-coupled contributions can be used to more precisely constrain the initial conditions and the transport properties of the medium in theoretical models. The multiparticle azimuthal cumulant method is used to measure the linear and mode-coupled contributions in the higher-order anisotropic flow, the mode-coupled response coefficients, and the correlations of the event plane angles for charged particles as functions of centrality and transverse momentum in Au+Au collisions at nucleon-nucleon center-of-mass energy sNN= 200 GeV. The results are compared to similar LHC measurements as well as to several viscous hydrodynamic calculations with varying initial conditions.
Published: 2020

24. Measurement of away-side broadening with self-subtraction of flow in Au+Au collisions at √sNN = 200 GeV

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, De La Barca Sánchez, MC, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL
Subjects: di-hadron correlations, Particle and Plasma Physics, jet, heavy-ion, Molecular, Nuclear, Nuclear Experiment, nucl-ex, Nuclear & Particles Physics, Atomic
Abstract: High transverse momentum (PT) particle production is suppressed owing to the parton (jet) energy loss in the hot dense medium created in relativistic heavy-ion collisions. Redistribution of energy at low-to-modest PT has been difficult to measure, owing to large anisotropic backgrounds. We report a data-driven method for background evaluation and subtraction, exploiting the away-side pseudorapidity gaps, to measure the jetlike correlation shape in Au+Au collisions at √SNN = 200 GeV in the STAR experiment. The correlation shapes, for trigger particles and various associated particle PT ranges within, are consistent with Gaussians, and their widths increase with centrality. The results indicate jet broadening in the medium created in central heavy-ion collisions.
Published: 2020

25. Measurement of away-side broadening with self-subtraction of flow in Au+Au collisions at GeV * * This work was supported in part by the Office of Nuclear Physics within the U.S. DOE Office of Science, the U.S. National Science Foundation, the Ministry of Education and Science of the Russian Federation, National Natural Science Foundation of China, Chinese Academy of Science, the Ministry of Science and Technology of China and the Chinese Ministry of Education, the Higher Education Sprout Project by Ministry of Education at NCKU, the National Research Foundation of Korea, Czech Science Foundation and Ministry of Education, Youth and Sports of the Czech Republic, Hungarian National Research, Development and Innovation Office, New National Excellency Programme of the Hungarian Ministry of Human Capacities, Department of Atomic Energy and Department of Science and Technology of the Government of India, the National Science Centre of Poland, the Ministry of Science, Education and Sports of the Republic of Croatia

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL
Subjects: Quality Education, di-hadron correlations, Particle and Plasma Physics, jet, heavy-ion, Molecular, Nuclear, nucl-ex, Atomic, Nuclear & Particles Physics
Abstract: High transverse momentum (PT) particle production is suppressed owing to the parton (jet) energy loss in the hot dense medium created in relativistic heavy-ion collisions. Redistribution of energy at low-to-modest PT has been difficult to measure, owing to large anisotropic backgrounds. We report a data-driven method for background evaluation and subtraction, exploiting the away-side pseudorapidity gaps, to measure the jetlike correlation shape in Au+Au collisions at √SNN = 200 GeV in the STAR experiment. The correlation shapes, for trigger particles and various associated particle PT ranges within, are consistent with Gaussians, and their widths increase with centrality. The results indicate jet broadening in the medium created in central heavy-ion collisions.
Published: 2020

26. Investigation of the linear and mode-coupled flow harmonics in Au+Au collisions at s N N = 200 GeV

Author: Collaboration, STAR, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, and Hu, Y
Subjects: Particle and Plasma Physics, Collectivity, Shear viscosity, Molecular, Nuclear, nucl-ex, Atomic, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Correlation
Abstract: Flow harmonics (vn) of the Fourier expansion for the azimuthal distributions of hadrons are commonly employed to quantify the azimuthal anisotropy of particle production relative to the collision symmetry planes. While lower order Fourier coefficients (v2 and v3) are more directly related to the corresponding eccentricities of the initial state, the higher-order flow harmonics (vn>3) can be induced by a mode-coupled response to the lower-order anisotropies, in addition to a linear response to the same-order anisotropies. These higher-order flow harmonics and their linear and mode-coupled contributions can be used to more precisely constrain the initial conditions and the transport properties of the medium in theoretical models. The multiparticle azimuthal cumulant method is used to measure the linear and mode-coupled contributions in the higher-order anisotropic flow, the mode-coupled response coefficients, and the correlations of the event plane angles for charged particles as functions of centrality and transverse momentum in Au+Au collisions at nucleon-nucleon center-of-mass energy sNN= 200 GeV. The results are compared to similar LHC measurements as well as to several viscous hydrodynamic calculations with varying initial conditions.
Published: 2020

27. Beam-energy dependence of the directed flow of deuterons in Au+Au collisions

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL
Subjects: Particle and Plasma Physics, Nuclear Theory, Molecular, Nuclear, Astrophysics::Cosmology and Extragalactic Astrophysics, Nuclear Experiment, nucl-ex, Atomic, Nuclear & Particles Physics
Abstract: We present a measurement of the first-order azimuthal anisotropy v1 of deuterons from Au+Au collisions at sNN=7.7, 11.5, 14.5, 19.6, 27, and 39 GeV recorded with the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The energy dependence of the v1(y) slope, dv1/dy|y=0, for deuterons, where y is the rapidity, is extracted for semicentral collisions (10%-40% centrality) and compared with that of protons. While the v1(y) slopes of protons are generally negative for sNN>10GeV, those for deuterons are consistent with zero, a strong enhancement of the v1(y) slope of deuterons is seen at the lowest collision energy (the largest baryon density) at sNN=7.7GeV. In addition, we report the transverse momentum dependence of v1 for protons and deuterons. The experimental results are compared with transport and coalescence models.
Published: 2020

28. Results on total and elastic cross sections in proton–proton collisions at s=200 GeV

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bueltmann, S, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL
Subjects: Particle and Plasma Physics, hep-ex, Molecular, Nuclear, Elastic scattering, nucl-ex, Diffraction, Nuclear & Particles Physics, Atomic, Mathematical Physics, Astronomical and Space Sciences, Proton-proton collisions
Abstract: We report results on the total and elastic cross sections in proton-proton collisions at s=200 GeV obtained with the Roman Pot setup of the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The elastic differential cross section was measured in the squared four-momentum transfer range 0.045≤−t≤0.135 GeV2. The value of the exponential slope parameter B of the elastic differential cross section dσ/dt∼e−Bt in the measured −t range was found to be B=14.32±0.09(stat.)−0.28+0.13(syst.) GeV−2. The total cross section σtot, obtained from extrapolation of the dσ/dt to the optical point at −t=0, is σtot=54.67±0.21(stat.)−1.38+1.28(syst.) mb. We also present the values of the elastic cross section σel=10.85±0.03(stat.)−0.41+0.49(syst.) mb, the elastic cross section integrated within the STAR t-range σeldet=4.05±0.01(stat.)−0.17+0.18(syst.) mb, and the inelastic cross section σinel=43.82±0.21(stat.)−1.44+1.37(syst.) mb. The results are compared with the world data.
Published: 2020

29. Results on total and elastic cross sections in proton–proton collisions at s = 200 GeV

Author: Collaboration, STAR, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bueltmann, S, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, and Hu, Y
Subjects: Particle and Plasma Physics, hep-ex, Molecular, Nuclear, Elastic scattering, nucl-ex, Diffraction, Atomic, Nuclear & Particles Physics, Mathematical Physics, Astronomical and Space Sciences, Proton-proton collisions
Abstract: We report results on the total and elastic cross sections in proton-proton collisions at s=200 GeV obtained with the Roman Pot setup of the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The elastic differential cross section was measured in the squared four-momentum transfer range 0.045≤−t≤0.135 GeV2. The value of the exponential slope parameter B of the elastic differential cross section dσ/dt∼e−Bt in the measured −t range was found to be B=14.32±0.09(stat.)−0.28+0.13(syst.) GeV−2. The total cross section σtot, obtained from extrapolation of the dσ/dt to the optical point at −t=0, is σtot=54.67±0.21(stat.)−1.38+1.28(syst.) mb. We also present the values of the elastic cross section σel=10.85±0.03(stat.)−0.41+0.49(syst.) mb, the elastic cross section integrated within the STAR t-range σeldet=4.05±0.01(stat.)−0.17+0.18(syst.) mb, and the inelastic cross section σinel=43.82±0.21(stat.)−1.44+1.37(syst.) mb. The results are compared with the world data.
Published: 2020

30. Beam energy dependence of net- Λ fluctuations measured by the STAR experiment at the BNL Relativistic Heavy Ion Collider

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, De La Barca Sánchez, MC, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Crawford, HJ, Csanád, M, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, L, Heppelmann, S, Herrmann, N, Holub, L, Hong, Y, Horvat, S, Huang, B, Huang, HZ, Huang, SL, Huang, T, Huang, X, and Humanic, TJ
Subjects: nucl-th, hep-ex, Nuclear Theory, hep-ph, Nuclear Experiment, nucl-ex
Abstract: The measurements of particle multiplicity distributions have generated considerable interest in understanding the fluctuations of conserved quantum numbers in the quantum chromodynamics (QCD) hadronization regime, in particular near a possible critical point and near the chemical freeze-out. Net-protons and net-kaons have been used as proxies for the net-baryon number and net-strangeness, respectively. We report the measurement of efficiency- and centrality-bin width-corrected cumulant ratios (C2/C1, C3/C2) of net-Λ distributions, in the context of both strangeness and baryon number conservation, as a function of collision energy, centrality, and rapidity. The results are for Au+Au collisions at five beam energies (sNN=19.6, 27, 39, 62.4, and 200 GeV) recorded with the Solenoidal Tracker at RHIC (STAR). We compare our results to the Poisson and negative binomial (NBD) expectations, as well as to ultrarelativistic quantum molecular dynamics (UrQMD) and hadron resonance gas (HRG) model predictions. Both NBD and Poisson baselines agree with data within the statistical and systematic uncertainties. UrQMD describes the measured net-ΛC1 and C3 at 200 GeV reasonably well but deviates from C2, and the deviation increases as a function of collision energy. The ratios of the measured cumulants show no features of critical fluctuations. The chemical freeze-out temperatures extracted from a recent HRG calculation, which was successfully used to describe the net-proton, net-kaon, and net-charge data, indicate Λ freeze-out conditions similar to those of kaons. However, large deviations are found when comparing with temperatures obtained from net-proton fluctuations. The net-Λ cumulants show a weak but finite dependence on the rapidity coverage in the acceptance of the detector, which can be attributed to quantum number conservation.
Published: 2020

31. Beam energy dependence of net-Λ fluctuations measured by the STAR experiment at the BNL Relativistic Heavy Ion Collider

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Crawford, HJ, Csanád, M, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, L, Heppelmann, S, Herrmann, N, Holub, L, Hong, Y, Horvat, S, Huang, B, Huang, HZ, Huang, SL, Huang, T, Huang, X, and Humanic, TJ
Subjects: Particle and Plasma Physics, nucl-th, hep-ex, Molecular, hep-ph, Nuclear, nucl-ex, Atomic, Nuclear & Particles Physics
Abstract: The measurements of particle multiplicity distributions have generated considerable interest in understanding the fluctuations of conserved quantum numbers in the quantum chromodynamics (QCD) hadronization regime, in particular near a possible critical point and near the chemical freeze-out. Net-protons and net-kaons have been used as proxies for the net-baryon number and net-strangeness, respectively. We report the measurement of efficiency- and centrality-bin width-corrected cumulant ratios (C2/C1, C3/C2) of net-Λ distributions, in the context of both strangeness and baryon number conservation, as a function of collision energy, centrality, and rapidity. The results are for Au+Au collisions at five beam energies (sNN=19.6, 27, 39, 62.4, and 200 GeV) recorded with the Solenoidal Tracker at RHIC (STAR). We compare our results to the Poisson and negative binomial (NBD) expectations, as well as to ultrarelativistic quantum molecular dynamics (UrQMD) and hadron resonance gas (HRG) model predictions. Both NBD and Poisson baselines agree with data within the statistical and systematic uncertainties. UrQMD describes the measured net-ΛC1 and C3 at 200 GeV reasonably well but deviates from C2, and the deviation increases as a function of collision energy. The ratios of the measured cumulants show no features of critical fluctuations. The chemical freeze-out temperatures extracted from a recent HRG calculation, which was successfully used to describe the net-proton, net-kaon, and net-charge data, indicate Λ freeze-out conditions similar to those of kaons. However, large deviations are found when comparing with temperatures obtained from net-proton fluctuations. The net-Λ cumulants show a weak but finite dependence on the rapidity coverage in the acceptance of the detector, which can be attributed to quantum number conservation.
Published: 2020

32. Measurement of D0 -meson + hadron two-dimensional angular correlations in Au+ Au collisions at sNN =200 GeV

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL
Subjects: Particle and Plasma Physics, High Energy Physics::Phenomenology, Molecular, High Energy Physics::Experiment, Nuclear, Nuclear Experiment, nucl-ex, Nuclear & Particles Physics, Atomic
Abstract: Open heavy-flavor hadrons provide unique probes of the medium produced in ultrarelativistic heavy-ion collisions. Due to their increased mass relative to light-flavor hadrons, long lifetime, and early production in hard-scattering interactions, they provide access to the full evolution of the partonic medium formed in heavy-ion collisions. This paper reports two-dimensional (2D) angular correlations between neutral D mesons and unidentified charged particles produced in minimum-bias Au+Au collisions at sNN=200GeV. D0 and D¯0 mesons are reconstructed via their weak decay to Kπ± using the Heavy Flavor Tracker in the Solenoidal Tracker at RHIC experiment. Correlations on relative pseudorapidity and azimuth (Δη,Δφ) are presented for peripheral, midcentral, and central collisions with D0 transverse momentum from 2-10GeV/c. Attention is focused on the 2D peaked correlation structure near the triggered D0 meson, the near-side (NS) peak, which serves as a proxy for a charm-quark-containing jet. The correlated NS yield of charged particles per D0 meson and the 2D widths of the NS peak increase significantly from peripheral to central collisions. These results are compared with similar correlations using unidentified charged particles, consisting primarily of light-flavor hadrons, at similar trigger particle momenta. Similar per-trigger yields and widths of the NS correlation peak are observed. The present results provide additional evidence that D0 mesons undergo significant interactions with the medium formed in heavy-ion collision and show, for the first time, significant centrality evolution of the NS 2D peak in the correlations of particles associated with a heavy-flavor hadron produced in these collisions.
Published: 2020

33. Measurement of D0-meson + hadron two-dimensional angular correlations in Au+Au collisions at sNN=200 GeV

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, and Huang, SL
Subjects: Particle and Plasma Physics, High Energy Physics::Phenomenology, Molecular, High Energy Physics::Experiment, Nuclear, Nuclear Experiment, nucl-ex, Atomic, Nuclear & Particles Physics
Abstract: Open heavy-flavor hadrons provide unique probes of the medium produced in ultrarelativistic heavy-ion collisions. Due to their increased mass relative to light-flavor hadrons, long lifetime, and early production in hard-scattering interactions, they provide access to the full evolution of the partonic medium formed in heavy-ion collisions. This paper reports two-dimensional (2D) angular correlations between neutral D mesons and unidentified charged particles produced in minimum-bias Au+Au collisions at sNN=200GeV. D0 and D¯0 mesons are reconstructed via their weak decay to Kπ± using the Heavy Flavor Tracker in the Solenoidal Tracker at RHIC experiment. Correlations on relative pseudorapidity and azimuth (Δη,Δφ) are presented for peripheral, midcentral, and central collisions with D0 transverse momentum from 2-10GeV/c. Attention is focused on the 2D peaked correlation structure near the triggered D0 meson, the near-side (NS) peak, which serves as a proxy for a charm-quark-containing jet. The correlated NS yield of charged particles per D0 meson and the 2D widths of the NS peak increase significantly from peripheral to central collisions. These results are compared with similar correlations using unidentified charged particles, consisting primarily of light-flavor hadrons, at similar trigger particle momenta. Similar per-trigger yields and widths of the NS correlation peak are observed. The present results provide additional evidence that D0 mesons undergo significant interactions with the medium formed in heavy-ion collision and show, for the first time, significant centrality evolution of the NS 2D peak in the correlations of particles associated with a heavy-flavor hadron produced in these collisions.
Published: 2020

34. Measurement of the central exclusive production of charged particle pairs in proton-proton collisions at s = 200 GeV with the STAR detector at RHIC

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Chu, X, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harabasz, S, Harris, JW, He, S, He, W, He, XH, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, and Huang, HZ
Subjects: Hadron-Hadron scattering, Quantum Physics, Particle and Plasma Physics, hep-ex, Forward physics, Molecular, Nuclear, Nuclear Experiment, nucl-ex, Diffraction, Atomic, Nuclear & Particles Physics, Mathematical Physics
Abstract: We report on the measurement of the Central Exclusive Production of charged particle pairs h+h− (h = π, K, p) with the STAR detector at RHIC in proton-proton collisions at s = 200 GeV. The charged particle pairs produced in the reaction pp → p′ + h+h− + p′ are reconstructed from the tracks in the central detector and identified using the specific energy loss and the time of flight method, while the forward-scattered protons are measured in the Roman Pot system. Exclusivity of the event is guaranteed by requiring the transverse momentum balance of all four final-state particles. Differential cross sections are measured as functions of observables related to the central hadronic final state and to the forward-scattered protons. They are measured in a fiducial region corresponding to the acceptance of the STAR detector and determined by the central particles’ transverse momenta and pseudorapidities as well as by the forward-scattered protons’ momenta. This fiducial region roughly corresponds to the square of the four-momentum transfers at the proton vertices in the range 0.04 GeV2< −t1, −t2< 0.2 GeV2, invariant masses of the charged particle pairs up to a few GeV and pseudorapidities of the centrally-produced hadrons in the range |η| < 0.7. The measured cross sections are compared to phenomenological predictions based on the Double Pomeron Exchange (DPE) model. Structures observed in the mass spectra of π+π− and K+K− pairs are consistent with the DPE model, while angular distributions of pions suggest a dominant spin-0 contribution to π+π− production. For π+π− production, the fiducial cross section is extrapolated to the Lorentz-invariant region, which allows decomposition of the invariant mass spectrum into continuum and resonant contributions. The extrapolated cross section is well described by the continuum production and at least three resonances, the f0(980), f2(1270) and f0(1500), with a possible small contribution from the f0(1370). Fits to the extrapolated differential cross section as a function of t1 and t2 enable extraction of the exponential slope parameters in several bins of the invariant mass of π+π− pairs. These parameters are sensitive to the size of the interaction region. [Figure not available: see fulltext.].
Published: 2020

35. First Measurement of Λ_{c} Baryon Production in Au+Au Collisions at sqrt[s_{NN}]=200 GeV

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, Huang, SL, Huang, T, and Huang, X
Subjects: STAR Collaboration, General Physics, Engineering, hep-ex, Physical Sciences, High Energy Physics::Experiment, Astrophysics::Cosmology and Extragalactic Astrophysics, Nuclear Experiment, nucl-ex, Mathematical Sciences
Abstract: We report on the first measurement of the charmed baryon Λ_{c}^{±} production at midrapidity (|y
Published: 2020

36. Measurement of the mass difference and the binding energy of the hypertriton and antihypertriton

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, MC, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, Huang, SL, and Huang, T
Subjects: nucl-th, hep-ex, Fluids & Plasmas, High Energy Physics::Phenomenology, Nuclear Theory, Physical Sciences, High Energy Physics::Experiment, Nuclear Experiment, nucl-ex, Mathematical Sciences
Abstract: According to the CPT theorem, which states that the combined operation of charge conjugation, parity transformation and time reversal must be conserved, particles and their antiparticles should have the same mass and lifetime but opposite charge and magnetic moment. Here, we test CPT symmetry in a nucleus containing a strange quark, more specifically in the hypertriton. This hypernucleus is the lightest one yet discovered and consists of a proton, a neutron and a Λ hyperon. With data recorded by the STAR detector1–3 at the Relativistic Heavy Ion Collider, we measure the Λ hyperon binding energy BΛ for the hypertriton, and find that it differs from the widely used value4 and from predictions5–8, where the hypertriton is treated as a weakly bound system. Our results place stringent constraints on the hyperon–nucleon interaction9,10 and have implications for understanding neutron star interiors, where strange matter may be present11. A precise comparison of the masses of the hypertriton and the antihypertriton allows us to test CPT symmetry in a nucleus with strangeness, and we observe no deviation from the expected exact symmetry.
Published: 2020

37. The STAR beam energy scan phase II physics and upgrades

Author: YANG, C, ADAMCZYK, L, ADKINS, JK, AGAKISHIEV, G, AGGARWAL, MM, AHAMMED, Z, ALEKSEEV, I, APARIN, A, ARKHIPKIN, D, ASCHENAUER, EC, ASHRAF, MU, ATTRI, A, AVERICHEV, GS, BAI, X, BAIRATHI, V, BELLWIED, R, BHASIN, A, BHATI, AK, BHATTARAI, P, BIELCIK, J, BIELCIKOVA, J, BLAND, LC, BORDYUZHIN, IG, BOUCHET, J, BRANDENBURG, JD, BRANDIN, AV, BUNZAROV, I, BUTTERWORTH, J, CAINES, H, SANCHEZ, MCDL, CAMPBELL, JM, CEBRA, D, CHAKABERIA, I, CHALOUPKA, P, CHANG, Z, CHATTERJEE, A, CHATTOPADHYAY, S, CHEN, X, CHEN, JH, CHENG, J, CHERNEY, M, CHRISTIE, W, CONTIN, G, CRAWFORD, HJ, DAS, S, DE SILVA, LC, DEBBE, RR, DEDOVICH, TG, DENG, J, DEREVSCHIKOV, AA, DI RUZZA, B, DIDENKO, L, DILKS, C, DONG, X, DRACHENBERG, JL, DRAPER, JE, DU, CM, DUNKELBERGER, LE, DUNLOP, JC, EFIMOV, LG, ENGELAGE, J, EPPLEY, G, ESHA, R, EVDOKIMOV, O, EYSER, O, FATEMI, R, FAZIO, S, FEDERIC, P, FEDORISIN, J, FENG, Z, FILIP, P, FISYAK, Y, FLORES, CE, FULEK, L, GAGLIARDI, CA, GARAND, D, GEURTS, F, GIBSON, A, GIRARD, M, GREINER, L, GROSNICK, D, GUNARATHNE, DS, GUO, Y, GUPTA, S, GUPTA, A, GURYN, W, HAMAD, AI, HAMED, A, HAGUE, R, HARRIS, JW, HE, L, HEPPELMANN, S, HIRSCH, A, HOFFMANN, GW, HORVAT, S, HUANG, T, HUANG, B, HUANG, X, HUANG, HZ, HUCK, P, HUMANIC, TJ, IGO, G, JACOBS, WW, JANG, H, JENTSCH, A, JIA, J, JIANG, K, JUDD, EG, KABANA, S, KALINLDN, D, KANG, K, KAUDER, K, KE, HW, KEANE, D, KECHECHYAN, A, KHAN, ZH, KIKOLA, DP, KISEL, I, KISIEL, A, KOCHENDA, L, KOETKE, DD, KOSARZEWSKI, LK, KRAISHAN, AF, KRAVTSOV, P, KRUEGER, K, KUMAR, L, LAMONT, MAC, LANDGRAF, JM, LANDRY, KD, LAURET, J, LEBEDEV, A, LEDNICKY, R, LEE, JH, LI, X, LI, Y, LI, C, LI, W, LIN, T, LISA, MA, LIU, F, LJUBICIC, T, LLOPE, WJ, LOMNITZ, M, LONGACRE, RS, LUO, X, LUO, S, MA, GL, MA, L, ME, YG, MA, R, MAGDY, N, MAJKA, R, MANION, A, MARGETIS, S, MARKERT, C, MATIS, HS, MCDONALD, D, MCKINZIE, S, MEEHAN, K, MEI, JC, MILLER, ZW, MINAEV, NG, MIODUSZEWSKI, S, MISHRA, D, MOHANTY, B, MONDAL, MM, MOROZOV, DA, MUSTAFA, MK, NANDI, BK, NASIM, M, NAYAK, TK, NIGMATKULOV, G, NIIDA, T, NOGACH, LV, NOH, SY, NOVAK, J, NURUSHEV, SB, ODYNIEC, G, OGAWA, A, OH, K, OKOROKOV, VA, OLVITT, D, PAGE, BS, PAK, R, PAN, YX, PANDIT, Y, PANEBRATSEV, Y, PAWLIK, B, PEI, H, PERKINS, C, PILE, P, PLUTA, J, PONIATOWSKA, K, PORTER, J, POSIK, M, POSKANZER, AM, PRUTHI, NK, PRZYBYCIEN, M, PUTSCHKE, J, QIU, H, QUINTERO, A, RAMACHANDRAN, S, RAY, RL, REED, R, RITTER, HG, ROBERTS, JB, ROGACHEVSKIY, OV, ROMERO, JL, RUAN, L, RUSNAK, J, RUSNAKOVA, O, SAHOO, NR, SAHU, PK, SAKREJDA, I, SALUR, S, SANDWEISS, J, SARKAR, A, SCHAMBACH, J, SCHARENBERG, RP, SCHMAH, AM, SCHMIDKE, WB, SCHMITZ, N, SEGER, J, SEYBOTH, P, SHAH, N, SHAHALIEV, E, SHANMUGANATHAN, PV, SHAO, M, SHARMA, A, SHARMA, B, SHARMA, MK, SHEN, WQ, SHI, Z, SHI, SS, SHOU, QY, SICHTERMANN, EP, SIKORA, R, SIMKO, M, SINGHA, S, SKOBY, MJ, SMIRNOV, D, SMIRNOV, N, SOLYST, W, SONG, L, SORENSEN, P, SPINKA, HM, SRIVASTAVA, B, STANISLAUS, TDS, STEPANOV, M, STOCK, R, STRIKHANOV, M, STRINGFELLOW, B, SUMBERA, M, SUMMA, B, SUN, Y, SUN, Z, SUN, XM, SURROW, B, SVIRIDA, DN, TANG, Z, TANG, AH, TARNOWSKY, T, TAWFIK, A, THADER, J, THOMAS, JH, TIMMINS, AR, TLUSTY, D, TODOROKI, T, TOKAREV, M, TRENTALANGE, S, TRIBBLE, RE, TRIBEDY, P, TRIPATHY, SK, TSAI, OD, ULLRICH, T, UNDERWOOD, DG, UPSAL, I, VAN BUREN, G, VAN NIEUWENHUIZEN, G, VANDENBROUCKE, M, VARMA, R, VASILIEV, AN, VERTESI, R, VIDEAEK, F, VOKAL, S, VOLOSHIN, SA, VOSSEN, A, WANG, H, WANG, F, WANG, Y, WANG, JS, WANG, G, WEBB, JC, WEBB, G, WEN, L, WESTFALL, GD, WIEMAN, H, WISSINK, SW, WITT, R, WU, Y, XIAO, ZG, XIE, W, XIE, G, XIN, K, XU, N, XU, QH, XU, Z, XU, J, XU, H, XU, YF, YANG, S, YANG, Y, YANG, Q, YE, Z, YI, L, YIP, K, YOO, IK, YU, N, ZBROSZCZYK, H, ZHA, W, ZHANG, Z, ZHANG, JB, ZHANG, S, ZHANG, XP, ZHANG, Y, ZHANG, J, ZHAO, J, ZHONG, C, ZHOU, L, ZHU, X, ZOULKARNEEVA, Y, and ZYZAK, M
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Physics::Instrumentation and Detectors, 010308 nuclear & particles physics, Qcd phase diagram, Detector, 01 natural sciences, law.invention, Nuclear physics, Upgrade, law, Critical point (thermodynamics), Baryon density, 0103 physical sciences, Detector Upgrade, High Energy Physics::Experiment, Physics Opportunity, Nuclear Experiment, 010306 general physics, Bes-Ii, Qcd Phase Diagram, Beam energy, Order of magnitude, Electron cooling
Abstract: The second phase of the Beam Energy Scan at RHIC, BPS-II, is scheduled for 2019-2020 and will explore with precision measurements the high baryon density region of the QCD phase diagram. The program will examine the energy region of interest determined from the results of BES-I. Some of the key measurements anticipated are: the net-protons kurtosis that could pinpoint the position of a critical point, the directed flow that might prove a softening of the EOS, and the chiral restoration in the dilepton channel. The measurements will be possible with the order of magnitude better statistics provided by the electron cooling upgrade of RHIC and with the detector upgrades planned to extend STAR's experimental reach. The upgrades are: the inner TPC sectors (iTPC), the Event Plane Detector (EPD), and the end -cap TOF (eTOF). We present the BES-II program details and the physics opportunities enabled by these upgrades.
Published: 2017
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38. Underlying event measurements in p+p collisions at s=200 GeV at RHIC

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, A, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, Huang, SL, and Huang, T
Subjects: Quantum Physics, Particle and Plasma Physics, hep-ex, Astrophysics::High Energy Astrophysical Phenomena, Molecular, High Energy Physics::Experiment, Nuclear, Nuclear Experiment, nucl-ex, Atomic, Nuclear & Particles Physics, Astronomical and Space Sciences
Abstract: Particle production sensitive to nonfactorizable and nonperturbative processes that contribute to the underlying event associated with a high transverse momentum (pT) jet in proton+proton collisions at s=200 GeV is studied with the STAR detector. Each event is divided into three regions based on the azimuthal angle with respect to the highest-pT jet direction: In the leading jet direction ("Toward"), opposite to the leading jet ("Away"), and perpendicular to the leading jet ("Transverse"). In the Transverse region, the average charged particle density is found to be between 0.4 and 0.6 and the mean transverse momentum
Published: 2020

39. Bulk properties of the system formed in Au+Au collisions at sNN =14.5 GeV at the BNL STAR detector

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Chen, Z, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanád, M, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, S, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, HZ, Huang, SL, and Huang, T
Subjects: Particle and Plasma Physics, hep-ex, Molecular, Nuclear, High Energy Physics::Experiment, hep-ph, Nuclear Experiment, nucl-ex, Atomic, Nuclear & Particles Physics
Abstract: We report systematic measurements of bulk properties of the system created in Au+Au collisions at sNN=14.5 GeV recorded by the STAR detector at the Relativistic Heavy Ion Collider (RHIC). The transverse momentum spectra of π±, K±, and p(p) are studied at midrapidity (|y
Published: 2020

40. Beam-energy dependence of identified two-particle angular correlations ins root s(NN)=7.7-200 GeV Au + Au collisions

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, Sanchez, M Calderon de la Barca, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanad, M, Das, S, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, B, Huang, HZ, Huang, SL, and Huang, T
Subjects: Nuclear Theory, Nuclear Experiment, nucl-ex
Abstract: The two-particle angular correlation functions, $R_2$, of pions, kaons, and protons in Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV were measured by the STAR experiment at RHIC. These correlations were measured for both like-sign and unlike-sign charge combinations and versus the centrality. The correlations of pions and kaons show the expected near-side ({\it i.e.}, at small relative angles) peak resulting from short-range mechanisms. The amplitudes of these short-range correlations decrease with increasing beam energy. However, the proton correlation functions exhibit strong anticorrelations in the near-side region. This behavior is observed for the first time in an A+A collision system. The observed anticorrelation is $p_{T}$-independent and decreases with increasing beam energy and centrality. The experimental results are also compared to the Monte Carlo models UrQMD, Hijing, and AMPT.
Published: 2020

41. Beam-energy dependence of identified two-particle angular correlations in sNN=7.7–200 GeV Au+Au collisions

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chen, D, Chen, JH, Chen, X, Cheng, J, Cherney, M, Chevalier, M, Choudhury, S, Christie, W, Crawford, HJ, Csanád, M, Das, S, Daugherity, M, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, CJ, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Francisco, A, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, W, He, X, Heppelmann, S, Herrmann, N, Hoffman, E, Holub, L, Hong, Y, Horvat, S, Hu, Y, Huang, B, Huang, HZ, and Huang, SL
Subjects: Particle and Plasma Physics, Nuclear Theory, Molecular, Nuclear, Nuclear Experiment, nucl-ex, Atomic, Nuclear & Particles Physics
Abstract: The two-particle angular correlation functions, $R_2$, of pions, kaons, and protons in Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV were measured by the STAR experiment at RHIC. These correlations were measured for both like-sign and unlike-sign charge combinations and versus the centrality. The correlations of pions and kaons show the expected near-side ({\it i.e.}, at small relative angles) peak resulting from short-range mechanisms. The amplitudes of these short-range correlations decrease with increasing beam energy. However, the proton correlation functions exhibit strong anticorrelations in the near-side region. This behavior is observed for the first time in an A+A collision system. The observed anticorrelation is $p_{T}$-independent and decreases with increasing beam energy and centrality. The experimental results are also compared to the Monte Carlo models UrQMD, Hijing, and AMPT.
Published: 2020

42. Charge-dependent pair correlations relative to a third particle in p + Au and d + Au collisions at RHIC

Author: Collaboration, STAR, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Atetalla, F, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Crawford, HJ, Csanád, M, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, L, Heppelmann, S, Herrmann, N, Holub, L, Hong, Y, Horvat, S, Huang, B, Huang, HZ, and Huang, SL
Subjects: nucl-th, hep-ex, High Energy Physics::Lattice, High Energy Physics::Phenomenology, Molecular, hep-ph, nucl-ex, Nuclear & Particles Physics, Atomic, Particle and Plasma Physics, Nuclear, Nuclear Experiment, Mathematical Physics, Astronomical and Space Sciences
Abstract: Quark interactions with topological gluon configurations can induce chirality imbalance and local parity violation in quantum chromodynamics. This can lead to electric charge separation along the strong magnetic field in relativistic heavy-ion collisions – the chiral magnetic effect (CME). We report measurements by the STAR collaboration of a CME-sensitive observable in p+Au and d+Au collisions at 200 GeV, where the CME is not expected, using charge-dependent pair correlations relative to a third particle. We observe strong charge-dependent correlations similar to those measured in heavy-ion collisions. This bears important implications for the interpretation of the heavy-ion data.
Published: 2019

43. Measurement of inclusive J/ψ suppression in Au+Au collisions at sNN=200 GeV through the dimuon channel at STAR

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Atetalla, F, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Crawford, HJ, Csanád, M, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, L, Heppelmann, S, Herrmann, N, Holub, L, Hong, Y, Horvat, S, Huang, B, Huang, HZ, Huang, SL, Huang, T, and Huang, X
Subjects: J/psi suppression, Nuclear Theory, Quark-gluon plasma, Molecular, Color-screening, nucl-ex, Nuclear & Particles Physics, Atomic, Particle and Plasma Physics, High Energy Physics::Experiment, Nuclear, Nuclear Experiment, Mathematical Physics, Astronomical and Space Sciences
Abstract: J/ψ suppression has long been considered a sensitive signature of the formation of the Quark-Gluon Plasma (QGP) in relativistic heavy-ion collisions. In this letter, we present the first measurement of inclusive J/ψ production at mid-rapidity through the dimuon decay channel in Au+Au collisions at sNN=200 GeV with the STAR experiment. These measurements became possible after the installation of the Muon Telescope Detector was completed in 2014. The J/ψ yields are measured in a wide transverse momentum (pT) range of 0.15 GeV/c to 12 GeV/c from central to peripheral collisions. They extend the kinematic reach of previous measurements at RHIC with improved precision. In the 0-10% most central collisions, the J/ψ yield is suppressed by a factor of approximately 3 for pT>5 GeV/c relative to that in p+p collisions scaled by the number of binary nucleon-nucleon collisions. The J/ψ nuclear modification factor displays little dependence on pT in all centrality bins. Model calculations can qualitatively describe the data, providing further evidence for the color-screening effect experienced by J/ψ mesons in the QGP.
Published: 2019

44. Measurement of inclusive J/ψ suppression in Au+Au collisions at s NN = 200 GeV through the dimuon channel at STAR

Author: Collaboration, STAR, Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Atetalla, F, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Crawford, HJ, Csanád, M, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, L, Heppelmann, S, Herrmann, N, Holub, L, Hong, Y, Horvat, S, Huang, B, Huang, HZ, and Huang, SL
Subjects: J/psi suppression, Nuclear Theory, Quark-gluon plasma, Molecular, Color-screening, nucl-ex, Atomic, Nuclear & Particles Physics, Particle and Plasma Physics, High Energy Physics::Experiment, Nuclear, Nuclear Experiment, Mathematical Physics, Astronomical and Space Sciences
Abstract: J/ψ suppression has long been considered a sensitive signature of the formation of the Quark-Gluon Plasma (QGP) in relativistic heavy-ion collisions. In this letter, we present the first measurement of inclusive J/ψ production at mid-rapidity through the dimuon decay channel in Au+Au collisions at sNN=200 GeV with the STAR experiment. These measurements became possible after the installation of the Muon Telescope Detector was completed in 2014. The J/ψ yields are measured in a wide transverse momentum (pT) range of 0.15 GeV/c to 12 GeV/c from central to peripheral collisions. They extend the kinematic reach of previous measurements at RHIC with improved precision. In the 0-10% most central collisions, the J/ψ yield is suppressed by a factor of approximately 3 for pT>5 GeV/c relative to that in p+p collisions scaled by the number of binary nucleon-nucleon collisions. The J/ψ nuclear modification factor displays little dependence on pT in all centrality bins. Model calculations can qualitatively describe the data, providing further evidence for the color-screening effect experienced by J/ψ mesons in the QGP.
Published: 2019

45. First Observation of the Directed Flow of D^{0} and D^{0}[over ¯] in Au+Au Collisions at sqrt[s_{NN}]=200 GeV

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Aschenauer, EC, Ashraf, MU, Atetalla, FG, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Contin, G, Crawford, HJ, Csanád, M, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Greiner, L, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, L, Heppelmann, S, Herrmann, N, Holub, L, Hong, Y, Horvat, S, Huang, B, Huang, HZ, and Huang, SL
Subjects: STAR Collaboration, General Physics, Engineering, nucl-th, hep-ex, Physical Sciences, High Energy Physics::Experiment, Nuclear Experiment, nucl-ex, Mathematical Sciences
Abstract: We report the first measurement of rapidity-odd directed flow (v_{1}) for D^{0} and D^{0}[over ¯] mesons at midrapidity (|y
Published: 2019

46. Longitudinal double-spin asymmetry for inclusive jet and dijet production in pp collisions at s =510 GeV

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Atetalla, F, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, de la Barca Sánchez, M Calderón, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Crawford, HJ, Csanád, M, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, L, Heppelmann, S, Herrmann, N, Holub, L, Hong, Y, Horvat, S, Huang, B, Huang, HZ, Huang, SL, and Huang, T
Subjects: Quantum Physics, Particle and Plasma Physics, hep-ex, Molecular, Nuclear, High Energy Physics::Experiment, Nuclear Experiment, nucl-ex, Atomic, Nuclear & Particles Physics, Astronomical and Space Sciences
Abstract: We report the first measurement of the inclusive jet and the dijet longitudinal double-spin asymmetries, ALL, at midrapidity in polarized pp collisions at a center-of-mass energy s=510 GeV. The inclusive jet ALL measurement is sensitive to the gluon helicity distribution down to a gluon momentum fraction of x≈0.015, while the dijet measurements, separated into four jet-pair topologies, provide constraints on the x dependence of the gluon polarization. Both results are consistent with previous measurements made at s=200 GeV in the overlapping kinematic region, x>0.05, and show good agreement with predictions from recent next-to-leading order global analyses.
Published: 2019

47. Polarization of Λ (Λ[over ¯]) Hyperons along the Beam Direction in Au+Au Collisions at sqrt[s_{NN}]=200 GeV

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Atetalla, F, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, Calderón de la Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Crawford, HJ, Csanád, M, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Gopal, K, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, L, Heppelmann, S, Herrmann, N, Holub, L, Hong, Y, Horvat, S, Huang, B, Huang, HZ, Huang, SL, and Huang, T
Subjects: STAR Collaboration, General Physics, Engineering, Physical Sciences, Nuclear Experiment, nucl-ex, Mathematical Sciences
Abstract: The Λ (Λ[over ¯]) hyperon polarization along the beam direction has been measured in Au+Au collisions at sqrt[s_{NN}]=200 GeV, for the first time in heavy-ion collisions. The polarization dependence on the hyperons' emission angle relative to the elliptic flow plane exhibits a second harmonic sine modulation, indicating a quadrupole pattern of the vorticity component along the beam direction, expected due to elliptic flow. The polarization is found to increase in more peripheral collisions, and shows no strong transverse momentum (p_{T}) dependence at p_{T} greater than 1 GeV/c. The magnitude of the signal is about 5 times smaller than those predicted by hydrodynamic and multiphase transport models; the observed phase of the emission angle dependence is also opposite to these model predictions. In contrast, the kinematic vorticity calculations in the blast-wave model tuned to reproduce particle spectra, elliptic flow, and the azimuthal dependence of the Gaussian source radii measured with the Hanbury Brown-Twiss intensity interferometry technique reproduce well the modulation phase measured in the data and capture the centrality and transverse momentum dependence of the polarization signal.
Published: 2019

48. Observation of Excess J/ψ Yield at Very Low Transverse Momenta in Au+Au Collisions at sqrt[s_{NN}]=200 GeV and U+U Collisions at sqrt[s_{NN}]=193 GeV

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Atetalla, F, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, Sánchez, M Calderón de la Barca, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, F-H, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Crawford, HJ, Csanad, M, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, L, Heppelmann, S, Herrmann, N, Holub, L, Hong, Y, Horvat, S, Huang, B, Huang, HZ, Huang, SL, Huang, T, and Huang, X
Subjects: STAR Collaboration, General Physics, Engineering, hep-ex, Physical Sciences, High Energy Physics::Experiment, Nuclear Experiment, Mathematical Sciences
Abstract: We report on the first measurements of J/ψ production at very low transverse momentum (p_{T}
Published: 2019

49. Measurements of the transverse-momentum-dependent cross sections of J/ψ production at mid-rapidity in proton+proton collisions at s=510 and 500 GeV with the STAR detector

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Atetalla, F, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Crawford, HJ, Csanád, M, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, L, Heppelmann, S, Herrmann, N, Holub, L, Hong, Y, Horvat, S, Huang, B, Huang, HZ, Huang, SL, Huang, T, and Huang, X
Subjects: Quantum Physics, Particle and Plasma Physics, hep-ex, Nuclear Theory, Molecular, High Energy Physics::Experiment, Nuclear, Nuclear Experiment, nucl-ex, Atomic, Nuclear & Particles Physics, Astronomical and Space Sciences
Abstract: We present measurements of the differential cross sections of inclusive J/ψ meson production as a function of transverse momentum (pTJ/ψ) using the μ+μ- and e+e- decay channels in proton+proton collisions at center-of-mass energies of 510 and 500 GeV, respectively, recorded by the STAR detector at the Relativistic Heavy Ion Collider. The measurement from the μ+μ- channel is for 0
Published: 2019

50. Collision-energy dependence of second-order off-diagonal and diagonal cumulants of net-charge, net-proton, and net-kaon multiplicity distributions in Au + Au collisions

Author: Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R, Aparin, A, Arkhipkin, D, Aschenauer, EC, Ashraf, MU, Atetalla, F, Attri, A, Averichev, GS, Bairathi, V, Barish, K, Bassill, AJ, Behera, A, Bellwied, R, Bhasin, A, Bhati, AK, Bielcik, J, Bielcikova, J, Bland, LC, Bordyuzhin, IG, Brandenburg, JD, Brandin, AV, Bryslawskyj, J, Bunzarov, I, Butterworth, J, Caines, H, Calderón De La Barca Sánchez, M, Cebra, D, Chakaberia, I, Chaloupka, P, Chan, BK, Chang, FH, Chang, Z, Chankova-Bunzarova, N, Chatterjee, A, Chattopadhyay, S, Chen, JH, Chen, X, Cheng, J, Cherney, M, Christie, W, Crawford, HJ, Csanád, M, Das, S, Dedovich, TG, Deppner, IM, Derevschikov, AA, Didenko, L, Dilks, C, Dong, X, Drachenberg, JL, Dunlop, JC, Edmonds, T, Elsey, N, Engelage, J, Eppley, G, Esha, R, Esumi, S, Evdokimov, O, Ewigleben, J, Eyser, O, Fatemi, R, Fazio, S, Federic, P, Fedorisin, J, Feng, Y, Filip, P, Finch, E, Fisyak, Y, Fulek, L, Gagliardi, CA, Galatyuk, T, Geurts, F, Gibson, A, Grosnick, D, Gupta, A, Guryn, W, Hamad, AI, Hamed, A, Harris, JW, He, L, Heppelmann, S, Herrmann, N, Holub, L, Hong, Y, Horvat, S, Huang, B, Huang, HZ, Huang, SL, Huang, T, and Huang, X
Subjects: Particle and Plasma Physics, hep-ex, Nuclear Theory, Molecular, High Energy Physics::Experiment, hep-ph, Nuclear, Nuclear Experiment, nucl-ex, Atomic, Nuclear & Particles Physics
Abstract: We report the first measurements of a complete second-order cumulant matrix of net-charge, net-proton, and net-kaon multiplicity distributions for the first phase of the beam energy scan program at the Relativistic Heavy Ion Collider. This includes the centrality and, for the first time, the pseudorapidity window dependence of both diagonal and off-diagonal cumulants in Au+Au collisions at sNN= 7.7-200 GeV. Within the available acceptance of |η
Published: 2019

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