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380 results on '"Bagdasarov, S."'

2. Ratios of bottom meson branching fractions involving J/psi mesons and determination of b quark fragmentation fractions

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amendolia, SR, Amidei, D, Antos, J, AnwayWiese, C, Aota, S, Apollinari, G, Asakawa, T, Ashmanskas, W, Atac, M, Azfar, F, AzziBacchetta, P, Bacchetta, N, Badgett, W, Bagdasarov, S, Bailey, M, Bao, J, deBarbaro, P, BarbaroGaltieri, A, Barnes, V, Barnett, B, and Barzi, E

Abstract

We report a measurement of the ratios of the decay rates of the B+, B0, and Bs 0 mesons into exclusive final states containing a J/ψ meson. The final states were selected from 19.6 pb-1 of pp̄ collisions recorded by the Collider Detector at Fermilab. These data are interpreted to determine the b quark fragmentation fractions fu, fd, and fs. We also determine the branching fractions for the decay modes B+ → J/ψK+, B+ → J/ψK*(892)+, B0 → J/ψK0, B0 → J/ψK*(892)0, and Bs 0 → J/ψφ(1020). We discuss the implications of these measurements to B meson decay models. © 1996 The American Physical Society.

Published
2016

4. Measurement of b(b)over-bar production correlations B-0(B)over-bar(0) mixing, and a limit on epsilon(B) in p(p)over-bar collisions at root s=1.8 TeV

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amendolia, SR, Amidei, D, Antos, J, AnwayWiese, C, Aota, S, Apollinari, G, Asakawa, T, Ashmanskas, W, Atac, M, Azfar, F, AzziBacchetta, P, Bacchetta, N, Badgett, W, Bagdasarov, S, Bailey, M, Bao, J, deBarbaro, P, BarbaroGaltieri, A, Barnes, V, Barnett, B, and Barzi, E

Published
2016
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5. STUDY OF T(T)OVER-BAR PRODUCTION IN P(P)OVER-BAR COLLISIONS USING TOTAL TRANSVERSE ENERGY

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, M, Amendolia, S, Amidei, D, Antos, J, Anwaywiese, C, Aota, S, Apollinari, G, Asakawa, T, Ashmanskas, W, Atac, M, Auchincloss, P, Azfar, F, Azzibacchetta, P, Bacchetta, N, Badgett, W, Bagdasarov, S, Bailey, M, Bao, J, Debarbaro, P, Barbarogaltieri, A, Barnes, V, and Barnett, B

Abstract

We analyze a sample of W+jet events collected with the Collider Detector at Fermilab (CDF) in pp» collisions at s=1.8 TeV to study tt» production. We employ a simple kinematical variable H, defined as the scalar sum of the transverse energies of the lepton, neutrino, and jets. For events with a W boson and four or more jets, the shape of the H distribution deviates by 3.8 standard deviations from that expected from known backgrounds to tt» production. However, this distribution agrees well with a linear combination of background and tt» events, the agreement being best for a top mass of 180 GeV/c2. © 1995 The American Physical Society.

Published
2016
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6. Search for new particles decaying into b(b)over-bar and produced in association with W bosons decaying into e nu or mu nu at the Fermilab Tevatron

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Asakawa, T, Ashmanskas, W, Atac, M, Azfar, F, AzziBacchetta, P, Bacchetta, N, Badgett, W, Bagdasarov, S, Bailey, M, Bao, J, deBarbaro, P, BarbaroGaltieri, A, Barnes, V, Barnett, B, Barone, M, and Barzi, E

Abstract

We search for new particles that decay into bb̄ and are produced with W bosons in pp̄ collisions at √s = 1.8 TeV. The search uses 109 ± 7 pb-1 accumulated by the CDF experiment at Fermilab. We select events with an ev or μv, and two jets, one of them b tagged. The number of events and the two-jet mass distribution are consistent with expectations. Using W + Higgs production as a model for the acceptance, we set an upper limit on the production cross section times branching ratio for the new particle ranging from 14 to 19 pb (95% C.L.) as the particle mass varies from 70 to 120 GeV/c2.

Published
2016
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7. Search for a W' boson via the decay mode W'-->munumu in 1.8 TeV pp collisions

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Arisawa, T, Asakawa, T, Ashmanskas, W, Atac, M, Azzi-Bacchetta, P, Bacchetta, N, Bagdasarov, S, Bailey, M, de Barbaro, P, Barbaro-Galtieri, A, Barnes, V, Barnett, B, Barone, M, Bauer, G, Bedeschi, F, and Behrends, S

Abstract

We report the results of a search for a W' boson produced in pp collisions at a center-of-mass energy of 1.8 TeV using a 107 pb-1 data sample recorded by the Collider Detector at Fermilab. We consider the decay channel W'-->andmunumu and search for anomalous production of high transverse mass munumu lepton pairs. We observe no excess of events above background and set limits on the rate of W' boson production and decay relative to standard model W boson production and decay using a fit of the transverse mass distribution observed. If we assume standard model strength couplings of the W' boson to quark and lepton pairs, we exclude a W' boson with invariant mass less than 660 GeV/c2 at 95% confidence level.

Published
2016
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10. Measurement of the B-0-(B)over-bar(0) oscillation frequency using pi-B meson charge-flavor correlations in p(p)over-bar collisions at root s=1.8 TeV

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amadon, A, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Arisawa, T, Asakawa, T, Ashmanskas, W, Atac, M, Azzi-Bacchetta, P, Bacchetta, N, Bagdasarov, S, Bailey, M, de Barbaro, P, Barbaro-Galtieri, A, Barnes, V, Barnett, B, Barone, M, Bauer, G, and Baumann, T

Abstract

We present a measurement of the B0 ↔ B̄0 oscillalion frequency using a flavor tagging method based on correlations of B meson flavor with the charge of other particles produced in pp̄ collisions at √s = 1.8 TeV. Such correlations are expected to arise from b quark hudronization and from B** decays. We partially reconstruct B mesons using the semileptonic decays B0 → D(*)-X and B+ rarr; -D̄0X. From the oscillation frequency, we obtain the mass difference between the two B0 mass eigenstates. Δmd = 0.471 -0.068+0.078(stat) ± 0.034(syst)ℏ ps-1, and measure the efficiency and purity of this flavor tagging method for both charged and neutral B mesons.

Published
2016

14. OBSERVATION OF TOP-QUARK PRODUCTION IN (P)OVER-BAR-P COLLISIONS WITH THE COLLIDER DETECTOR AT FERMILAB

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, M, Amendolia, S, Amidei, D, Antos, J, Anwaywiese, C, Aota, S, Apollinari, G, Asakawa, T, Ashmanskas, W, Atac, M, Auchincloss, P, Azfar, F, Azzibacchetta, P, Bacchetta, N, Badgett, W, Bagdasarov, S, Bailey, M, Bao, J, Debarbaro, P, Barbarogaltieri, A, Barnes, V, and Barnett, B

Abstract

We establish the existence of the top quark using a 67 pb-1 data sample of p̄p collisions at s=1.8 TeV collected with the Collider Detector at Fermilab (CDF). Employing techniques similar to those we previously published, we observe a signal consistent with tt̄ decay to WWbb̄, but inconsistent with the background prediction by 4.8σ. Additional evidence for the top quark is provided by a peak in the reconstructed mass distribution. We measure the top quark mass to be 176±8(stat)±10(syst) GeV/c2, and the tt̄ production cross section to be 6.8-2.4+3.6 pb. © 1995 The American Physical Society.

Published
2016

15. Properties of photon plus two-jet events in (p)over-bar-p collisions at root s=1.8 TeV

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Asakawa, T, Ashmanskas, W, Atac, M, Azfar, F, Azzi-Bacchetta, P, Bacchetta, N, Badgett, W, Bagdasarov, S, Bailey, M, Bao, J, de Barbaro, P, Barbaro-Galtieri, A, Barnes, V, Barnett, B, Barone, M, and Barzi, E

Abstract

We present the first general measurements (invariant-mass, transverse-energy, and angular distributions) of the process, p̄p→γ+2 jets+X, using data collected by the CDF at Fermilab. We compare the data with predictions from a tree-level QCD calculation and the PYTHIA shower Monte Carlo program. Our data sample is particularly sensitive to contributions from initial- and final-state radiation of photons and jets. Using the PYTHIA Monte Carlo program, we contrast the kinematical distributions for direct photon production with those for initial- and final-state photon radiation (bremsstrahlung). Based on the angular distributions, we find that our data favor a mixture of bremsstrahlung and direct photon production, as predicted, over either process alone.

Published
2016
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20. Observation of B-c mesons in p(p)over-bar collisions at root s=1.8 TeV

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amadon, A, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Arisawa, T, Asakawa, T, Ashmanskas, W, Atac, M, Azzi-Bacchetta, P, Bacchetta, N, Bagdasarov, S, Bailey, M, de Barbaro, P, Barbaro-Galtieri, A, Barnes, V, Barnett, B, Barone, M, Bauer, G, and Baumann, T

Published
2016
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21. Measurement of B hadron lifetimes using J/psi final states at CDF

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amadon, A, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Arisawa, T, Asakawa, T, Ashmanskas, W, Atac, M, Azfar, F, Azzi-Bacchetta, P, Bacchetta, N, Bagdasarov, S, Bailey, M, de Barbaro, P, Barbaro-Galtieri, A, Barnes, V, Barnett, B, Barone, M, and Bauer, G

Abstract

The average bottom-hadron and individual B+, B0, and Bs0 meson lifetimes have been determined using decays with a J/ψ→μ+μ- in the final state. The data sample consists of 110 pb-1 of p̄p collisions at √s =1.8 TeV collected by the CDF detector at the Fermilab Tevatron collider during 1992-1995. For the average lifetime of B hadrons decaying into J/ψ+X, we obtain =1.533±0.015(stat)-0.031+0.035(syst) ps. For the B+ and B0 meson lifetimes, we determine τ(B+)=1.68±0.07(stat) ±0.02(syst) ps, τ(B0)=1.58 ±0.09(stat) ±0.02(syst) ps, and τ(B+)/τ(B0)=1.06±0.07(stat) ±0.02(syst). For the Bs0 meson lifetime, we find τ(Bs0)=1.34-0.19+0.23(stat) ±0.05(syst) ps.

Published
2016

23. Kinematics of t(t)over-bar events at CDF

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amadon, A, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Arisawa, T, Asakawa, T, Ashmanskas, W, Atac, M, Azzi-Bacchetta, P, Bacchetta, N, Bagdasarov, S, Bailey, M, de Barbaro, P, Barbaro-Galtieri, A, Barnes, V, Barnett, B, Barone, M, Bauer, G, and Baumann, T

Published
2016

28. Measurement of the B-S(0) meson lifetime using semileptonic decays

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amadon, A, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Arisawa, T, Asakawa, T, Ashmanskas, W, Atac, M, Azzi-Bacchetta, P, Bacchetta, N, Bagdasarov, S, Bailey, M, de Barbaro, P, Barbaro-Galtieri, A, Barnes, V, Barnett, B, Barone, M, Bauer, G, and Baumann, T

Published
2016
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29. Search for flavor-changing neutral current B meson decays in p(p)over-bar collisions at root s=1.8 TeV

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amendolia, SR, Amidei, D, Antos, J, AnwayWise, C, Aota, S, Apollinari, G, Asakawa, T, Ashmanskas, W, Atac, M, Azfar, F, AzziGaltieri, P, Bacchetta, N, Badgett, W, Bagdasarov, S, Bailey, M, Bao, J, deBarbaro, P, BarbaroGaltieri, A, Barnes, V, Barnett, B, and Barzi, E

Abstract

We report on a search for the flavor-changing neutral current decays B d,s 0 → μ+μ-, B+ → μ+μ-K+ and B0 → μ+μ-K*0 using data from pp̄ collisions at √s = 1.8 TeV, collected with the Collider Detector at Fermilab during the 1992-1993 running period. We find no indication of such decays, and we set the following 90% confidence level upper limits on branching ratios: B(B0 → μ+μ-) < 1.6 × 10-6, B(BS 0 → μ+μ-) < 8.4 × 10-6, B(B+ → μ+μ-K+) < 1.0 × 10-5, and B(B0 → μ+μ-K*0) < 2.5 × 10-5.

Published
2016

30. Events with a rapidity gap between jets in (p)over-bar-p collisions at root s=630 GeV

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amadon, A, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Arisawa, T, Asakawa, T, Ashmanskas, W, Atac, M, Azzi-Bacchetta, P, Bacchetta, N, Bagdasarov, S, Bailey, M, de Barbaro, P, Barbaro-Galtieri, A, Barnes, V, Barnett, B, Barone, M, Bauer, G, and Baumann, T

Published
2016

35. Measurement of the lifetime of the B-s(0) meson using the exclusive decay mode B-s(0)->J/psi phi

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amendolia, SR, Amidei, D, Antos, J, AnwayWiese, C, Aota, S, Apollinari, G, Asakawa, T, Ashmanskas, W, Atac, M, Azfar, F, AzziBacchetta, P, Bacchetta, N, Badgett, W, Bagdasarov, S, Bailey, M, Bao, J, deBarbaro, P, BarbaroGaltieri, A, Barnes, V, Barnett, B, and Barzi, E

Abstract

The lifetime of the Bs 0 meson is measured using the exclusive decay mode Bs 0 → J / ψ φ, where J/ψ → μ+μ- and φ → K+K-. The data sample consists of 110 pb-1 of p p̄ collisions at √s = 1.8 TeV, collected by the CDF detector at the Fermilab Tevatron collider during 1992-1995. We find 58 ± 12 signal events, and the Bs 0 meson lifetime is determined to be τBs0; = 1.34-0.19 +0.23(stat) ± 0.05(syst) ps. This result is consistent with previous measurements of the Bs 0, B+, and Bd 0 meson lifetimes and with theoretical predictions.

Published
2016

36. Measurement of the differential cross section for events with large total transverse energy in p(p)over-bar collisions at root s=1.8 TeV

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amadon, A, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Arisawa, T, Asakawa, T, Ashmanskas, W, Atac, M, Azzi-Bacchetta, P, Bacchetta, N, Bagdasarov, S, Bailey, M, de Barbaro, P, Barbaro-Galtieri, A, Barnes, V, Barnett, B, Barone, M, Bauer, G, and Baumann, T

Abstract

We present a measurement of the differential cross section dσ/dΣETjet for the production of multijet events in pp̄ collisions where the sum is over all jets with transverse energy ETjet > ETmin. The measured cross section for events with ΣETjet > 320 GeV is compared to (αs3) perturbative QCD predictions and QCD parton shower Monte Carlo predictions. The agreement between the (αs3) predicted and observed event rates is reasonable for ETmin = 100 GeV, but poorer for ETmin = 20 GeV.

Published
2016

37. Measurement of B-0-(B)over-bar(0) flavor oscillations using jet-charge and lepton flavor tagging in p(p)over-bar collisions at root s=1.8 TeV

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Arisawa, T, Asakawa, T, Ashmanskas, W, Atac, M, Azzi-Bacchetta, P, Bacchetta, N, Bagdasarov, S, Bailey, M, de Barbaro, P, Barbaro-Galtieri, A, Barnes, V, Barnett, B, Barone, M, Bauer, G, Baumann, T, and Bedeschi, F

Published
2016
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38. Measurement of the top quark mass and t(t)over-bar production cross section from dilepton events at the collider detector at Fermilab

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amadon, A, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Arisawa, T, Asakawa, T, Ashmanskas, W, Atac, M, Azzi-Baccehtta, P, Bacchetta, N, Bagdasarov, S, Bailey, M, de Barbaro, P, Barbaro-Galtieri, A, Barnes, V, Barnett, B, Barone, M, Bauer, G, and Baumann, T

Published
2016
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41. Search for flavor-changing neutral current decays of the top quark in p(p)over-bar collisions at root s = 1.8 TeV

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Asakawa, T, Ashmanskas, W, Atac, M, Azfar, F, Azzi-Bacchetta, P, Bacchetta, N, Badgett, W, Bagdasarov, S, Bailey, M, Bao, J, de Barbaro, P, Barbaro-Galtieri, A, Barnes, V, Barnett, B, Barone, M, and Barzi, E

Abstract

We search for the flavor-changing neutral current decays of the top quark t → qy and t → qZ (here q represents the c and u quarks) in pp collisions at √ s = 1.8 TeV. We use a dataset (∫ dt ∼ 110 pb-1) collected during the 1992-1995 run of the Collider Detector at Fermilab. We set 95% confidence level limits on the branching fractions B(t → qy) < 3.2% and B(t → qZ) < 33%, consistent with the standard model.

Published
2016

44. Measurement of the branching fraction B(B-u(+)->J/psi pi(+)) and search for B-c(+)->J/psi pi(+)

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amendolia, SR, Amidei, D, Antos, J, AnwayWiese, C, Aota, S, Apollinari, G, Asakawa, T, Ashmanskas, W, Atac, M, Azfar, F, AzziBacchetta, P, Bacchetta, N, Badgett, W, Bagdasarov, S, Bailey, M, Bao, J, deBarbaro, P, BarbaroGaltieri, A, Barnes, V, Barnett, B, and Barzi, E

Abstract

We report on a measurement of the branching fraction of the Cabibbo-suppressed decay Bu +→J/ψπ+ , where J/ψ→μ+μ-. The data were collected by the Collider Detector at Fermilab during 1992-1995 and correspond to an integrated luminosity of 110 pb-1 in p̄p collisions at √s = 1.8 TeV. A signal of 289 +10 events is observed and we determine the ratio of branching fractions B(Bu +→J/ψπ+)/B(Bu +→J/ψK+) to be [5.0-1.7 +1.9(stat) ± 0.1(syst)]%. Using the world average value for B(Bu +→J/ψK+), we calculate the branching fraction B(Bu +→J/ψπ+) to be (5.0-1.9 +2.1) × 10-5. We also search for the decay Bc +→J/ψπ+ and report a 95% confidence level limit on σ(Bc +)B(Bc +→ J/ψπ+)/σ(Bu +)B(Bu +→J/ψK+) as a function of the Bc + lifetime.

Published
2016
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45. Limits on quark-lepton compositeness scales from dileptons produced in 1.8 TeV p(p)over-bar collisions

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Asakawa, T, Ashmanskas, W, Atac, M, Azfar, F, AzziBacchetta, P, Bacchetta, N, Badgett, W, Bagdasarov, S, Bailey, M, Bao, J, deBarbaro, P, BarbaroGaltieri, A, Barnes, V, Barnett, B, Barone, M, and Barzi, E

Abstract

The dilepton mass spectrum in pp̄ → l+l- + X interactions is studied using dielectrons (ee) and dimuons (μμ) in 110 pb-1 of data collected with the Collider Detector at Fermilab. The data are consistent with standard model predictions. The mass spectrum, being a probe for new physics, is examined for new interactions of quarks and leptons from a common composite structure. Assuming a contact interaction with the conventional coupling g0 2/4π = 1, limits on chiral quark-electron and quark-muon compositeness scales in the range of 2.5 to 4.2 TeV are obtained.

Published
2016
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48. Search for the decays B-s(0),B-d(0)-> e(+/-)mu(-/+) and Pati-Salam leptoquarks

Author

Abe, F, Akimoto, H, Akopian, A, Albrow, MG, Amadon, A, Amendolia, SR, Amidei, D, Antos, J, Aota, S, Apollinari, G, Arisawa, T, Asakawa, T, Ashmanskas, W, Atac, M, Azzi-Bacchetta, P, Bacchetta, N, Bagdasarov, S, Bailey, M, de Barbaro, P, Barbaro-Galtieri, A, Barnes, V, Barnett, B, Barone, M, Bauer, G, and Baumann, T

Published
2016

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