The Experts below are selected from a list of 20343 Experts worldwide ranked by ideXlab platform
S Chatrchyan - One of the best experts on this subject based on the ideXlab platform.
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search for flavor changing Neutral Currents in top quark decays t to zq in pp collisions at sqrt s 8 tev
Physical Review Letters, 2014Co-Authors: S Chatrchyan, V Khachatryan, A M Sirunyan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Ero, C Fabjan, M FriedlAbstract:A search for flavor-changing Neutral Currents in top-quark decays t to Zq is performed in events produced from the decay chain t t-bar to Zq+Wb, where both vector bosons decay leptonically, producing a final state with three leptons (electrons or muons). A dataset collected with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 19.7 inverse femtobarns of proton-proton collisions at a center-of-mass energy of 8 TeV. No excess is seen in the observed number of events relative to the standard model prediction; thus no evidence for flavor-changing Neutral Currents in top-quark decays is found. A combination with a previous search at 7 TeV excludes a t to Zq branching fraction greater than 0.05% at the 95% confidence level.
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Search for flavor-changing Neutral Currents in top-quark decays t to Zq in pp collisions at sqrt(s)=8 TeV
Physical Review Letters, 2014Co-Authors: S Chatrchyan, S. Baffioni, F. Beaudette, P. Busson, C. Charlot, N. Daci, T. Dahms, M. Dalchenko, L. Dobrzynski, A. FlorentAbstract:A search for flavor-changing Neutral Currents in top-quark decays t to Zq is performed in events produced from the decay chain t t-bar to Zq+Wb, where both vector bosons decay leptonically, producing a final state with three leptons (electrons or muons). A dataset collected with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 19.7 inverse femtobarns of proton-proton collisions at a center-of-mass energy of 8 TeV. No excess is seen in the observed number of events relative to the standard model prediction; thus no evidence for flavor-changing Neutral Currents in top-quark decays is found. A combination with a previous search at 7 TeV excludes a t to Zq branching fraction greater than 0.05% at the 95% confidence level.
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search for flavor changing Neutral Currents in top quark decays in pp collisions at 7 tev
Physics Letters B, 2013Co-Authors: S Chatrchyan, V Khachatryan, A M Sirunyan, A Tumasyan, W Adam, E Aguilo, T Bergauer, M Dragicevic, J Ero, C FabjanAbstract:The results of a search for flavor changing Neutral Currents in top quark decays t→Zqt→Zq in events with a topology compatible with the decay chain View the MathML sourcett¯→Wb+Zq→lνb+llq are presented. The search is performed with a data sample corresponding to an integrated luminosity of 5.0 fb−15.0 fb−1 of proton–proton collisions at a center-of-mass energy of 7 TeV, collected with the CMS detector at the LHC. The observed number of events agrees with the standard model prediction and no evidence for flavor changing Neutral Currents in top quark decays is found. A t→Zqt→Zq branching fraction greater than 0.21% is excluded at the 95% confidence level.
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Search for flavor changing Neutral Currents in top quark decays in pp collisions at 7 TeV
Physics Letters B, 2013Co-Authors: S Chatrchyan, M. Besancon, S. Choudhury, M. Dejardin, D. Denegri, B. Fabbro, J.l. Faure, F. Ferri, S. Ganjour, A. GivernaudAbstract:The results of a search for flavor changing Neutral Currents in top quark decays t to Zq in events with a topology compatible with the decay chain t t-bar to Wb+Zq to ell nu b + ell ell q are presented. The search is performed with a data sample corresponding to an integrated luminosity of 5.0 inverse femtobarns of proton-proton collisions at a center-of-mass energy of 7 TeV, collected with the CMS detector at the LHC. The observed number of events agrees with the standard model prediction and no evidence for flavor changing Neutral Currents in top quark decays is found. A t to Zq branching fraction greater than 0.24% is excluded at the 95% confidence level.
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search for same sign top quark pair production at sqrt s 7 tev and limits on flavour changing Neutral Currents in the top sector
Journal of High Energy Physics, 2011Co-Authors: L Quertenmont, S Chatrchyan, S Basegmez, G Bruno, J Caudron, L Ceard, Eduardo Cortina Gil, Jerome De Favereau De Jeneret, C Delaere, D FavartAbstract:An inclusive search for same-sign top-quark pair production in pp collisions at sqrt(s) = 7 TeV is performed using a data sample recorded with the CMS detector in 2010, corresponding to an integrated luminosity of 35 inverse picobarns. This analysis is motivated by recent studies of p p-bar to t t-bar reporting mass-dependent forward-backward asymmetries larger than expected from the standard model. These asymmetries could be due to Flavor Changing Neutral Currents (FCNC) in the top sector induced by t-channel exchange of a massive Neutral vector boson (Z'). Models with such a Z' also predict enhancement of same-sign top-pair production in pp or p p-bar collisions. Limits are set as a function of the Z'mass and its couplings to u and t quarks. These limits disfavour the FCNC interpretation of the Tevatron results.
S. Ganjour - One of the best experts on this subject based on the ideXlab platform.
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Search for top quark decays via Higgs-boson-mediated flavor-changing Neutral Currents in pp collisions at sqrt(s) = 8 TeV
Journal of High Energy Physics, 2017Co-Authors: V Khachatryan, M. Besancon, M. Dejardin, D. Denegri, B. Fabbro, J.l. Faure, F. Ferri, F. Couderc, C. Favaro, S. GanjourAbstract:A search is performed for Higgs-boson-mediated flavor-changing Neutral Currents in the decays of top quarks. The search is based on proton-proton collision data corresponding to an integrated luminosity of 19.7 inverse-femtobarns at a center-of-mass energy of 8 TeV collected with the CMS detector at the LHC. Events in which a top quark pair is produced with one top quark decaying into a charm or up quark and a Higgs boson (H), and the other top quark decaying into a bottom quark and a W boson are selected. The Higgs boson in these events is assumed to subsequently decay into either dibosons or difermions. No significant excess is observed above the expected standard model background, and an upper limit at the 95% confidence level is set on the branching fraction B(t -> Hc) of 0.40% and B(t -> Hu) of 0.55%, where the expected upper limits are 0.43% and 0.40\%, respectively. These results correspond to upper limits on the square of the flavor-changing Higgs boson Yukawa couplings | lambda[tc]^H |^2 < 6.9E-3 and | lambda[tu]^H |^2 < 9.8E-3.
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Search for flavor changing Neutral Currents in top quark decays in pp collisions at 7 TeV
Physics Letters B, 2013Co-Authors: S Chatrchyan, M. Besancon, S. Choudhury, M. Dejardin, D. Denegri, B. Fabbro, J.l. Faure, F. Ferri, S. Ganjour, A. GivernaudAbstract:The results of a search for flavor changing Neutral Currents in top quark decays t to Zq in events with a topology compatible with the decay chain t t-bar to Wb+Zq to ell nu b + ell ell q are presented. The search is performed with a data sample corresponding to an integrated luminosity of 5.0 inverse femtobarns of proton-proton collisions at a center-of-mass energy of 7 TeV, collected with the CMS detector at the LHC. The observed number of events agrees with the standard model prediction and no evidence for flavor changing Neutral Currents in top quark decays is found. A t to Zq branching fraction greater than 0.24% is excluded at the 95% confidence level.
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Search for Same-Sign Top-Quark Pair Production at sqrt(s) = 7 TeV and Limits on Flavour Changing Neutral Currents in the Top Sector
Journal of High Energy Physics, 2011Co-Authors: S Chatrchyan, M. Besancon, S. Choudhury, M. Dejardin, D. Denegri, B. Fabbro, J.l. Faure, F. Ferri, D. Sillou, S. GanjourAbstract:An inclusive search for same-sign top-quark pair production in pp collisions at sqrt(s) = 7 TeV is performed using a data sample recorded with the CMS detector in 2010, corresponding to an integrated luminosity of 35 inverse picobarns. This analysis is motivated by recent studies of p p-bar to t t-bar reporting mass-dependent forward-backward asymmetries larger than expected from the standard model. These asymmetries could be due to Flavor Changing Neutral Currents (FCNC) in the top sector induced by t-channel exchange of a massive Neutral vector boson (Z'). Models with such a Z' also predict enhancement of same-sign top-pair production in pp or p p-bar collisions. Limits are set as a function of the Z'mass and its couplings to u and t quarks. These limits disfavour the FCNC interpretation of the Tevatron results.
B. Abbott - One of the best experts on this subject based on the ideXlab platform.
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search for flavor changing Neutral Currents in top quark decays t hc and t hu in multilepton final states in proton proton collisions at s 13 tev with the atlas detector
Physical Review D, 2018Co-Authors: M Aaboud, B. Abbott, G Aad, Ovsat Abdinov, B Abeloos, Deshan Kavishka Abhayasinghe, Syed Haider Abidi, O S Abouzeid, N L AbrahamAbstract:Flavor-changing Neutral Currents are not present in the Standard Model at tree level and are suppressed in loop processes by the unitarity of the Cabibbo-Kobayashi-Maskawa matrix; the corresponding ...
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Search for flavor changing Neutral Currents in decays of top quarks
Physics Letters B, 2011Co-Authors: V.m. Abazov, B. Abbott, B.s. Acharya, M. Adams, T. Adams, G.d. Alexeev, G. Alkhazov, A. Alton, G. Alverson, G.a. AlvesAbstract:We present a search for flavor changing Neutral Currents in decays of top quarks. The analysis is based on a search for ttbar -> l'null + jets (l, l' = e, mu) final states using 4.1 fb^-1 of integrated luminosity of ppbar collisions at sqrt(s) = 1.96 TeV. We extract limits on the branching ratio B(t -> Zq) (q = u, c quarks), assuming anomalous tuZ or tcZ couplings. We do not observe any sign of such anomalous coupling and set a limit of B < 3.2% at 95% C.L.
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search for flavor changing Neutral Currents via quark gluon couplings in single top quark production using 2 3 fb 1 of pp collisions
Physics Letters B, 2010Co-Authors: V.m. Abazov, B. Abbott, B.s. Acharya, T. Adams, G.d. Alexeev, G. Alkhazov, A. Alton, M Abolins, M R Adams, G. AlversonAbstract:We present a search for flavor changing Neutral Currents via quark-gluon couplings in a sample of single top quark final states corresponding to 2.3 fb(-1) of integrated luminosity collected with the DO detector at the Fermilab Tevatron Collider. We select events containing a single top quark candidates with an additional jet, and obtain separation between signal and background using Bayesian neural networks. We find consistency between background expectation and observed data, and set limits on flavor changing Neutral current gluon couplings of the top quark to up quarks (tgu) and charm quarks (tgc). The cross section limits at the 95% C.L. are sigma(tgu) gu) gc) < 3.9 x 10(-3).
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search for flavor changing Neutral Currents in single top quark production using 2 3 fb 1 of p bar p collisions
arXiv: High Energy Physics - Experiment, 2010Co-Authors: V.m. Abazov, B. Abbott, B.s. Acharya, Jinr Dubna, U Oklahoma, M Abolins, Tata Inst, M R Adams, Chicago Illinois U, T. AdamsAbstract:We present a search for flavor changing Neutral Currents via quark-gluon couplings in a sample of single top quark final states corresponding to 2.3 fb^-1 of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider. We select events containing a single top quark candidates with an additional jet, and obtain separation between signal and background using Bayesian neural networks. We find consistency between background expectation and observed data, and set limits on flavor changing Neutral current gluon couplings of the top quark to up quarks (tgu) and charm quarks (tgc). The cross section limits at the 95% C.L. are sigma_tgu gu) gc)<3.9*10^-3.
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Search for flavor changing Neutral Currents via quark–gluon couplings in single top quark production using 2.3 fb^-1 of ppbar collisions
Physics Letters B, 2010Co-Authors: V.m. Abazov, B. Abbott, B.s. Acharya, M. Adams, T. Adams, G.d. Alexeev, G. Alkhazov, A. Alton, M Abolins, G. AlversonAbstract:We present a search for flavor changing Neutral Currents via quark-gluon couplings in a sample of single top quark final states corresponding to 2.3 fb^-1 of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider. We select events containing a single top quark candidates with an additional jet, and obtain separation between signal and background using Bayesian neural networks. We find consistency between background expectation and observed data, and set limits on flavor changing Neutral current gluon couplings of the top quark to up quarks (tgu) and charm quarks (tgc). The cross section limits at the 95% C.L. are sigma_tgu
V Khachatryan - One of the best experts on this subject based on the ideXlab platform.
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Search for top quark decays via Higgs-boson-mediated flavor-changing Neutral Currents in pp collisions at sqrt(s) = 8 TeV
Journal of High Energy Physics, 2017Co-Authors: V Khachatryan, M. Besancon, M. Dejardin, D. Denegri, B. Fabbro, J.l. Faure, F. Ferri, F. Couderc, C. Favaro, S. GanjourAbstract:A search is performed for Higgs-boson-mediated flavor-changing Neutral Currents in the decays of top quarks. The search is based on proton-proton collision data corresponding to an integrated luminosity of 19.7 inverse-femtobarns at a center-of-mass energy of 8 TeV collected with the CMS detector at the LHC. Events in which a top quark pair is produced with one top quark decaying into a charm or up quark and a Higgs boson (H), and the other top quark decaying into a bottom quark and a W boson are selected. The Higgs boson in these events is assumed to subsequently decay into either dibosons or difermions. No significant excess is observed above the expected standard model background, and an upper limit at the 95% confidence level is set on the branching fraction B(t -> Hc) of 0.40% and B(t -> Hu) of 0.55%, where the expected upper limits are 0.43% and 0.40\%, respectively. These results correspond to upper limits on the square of the flavor-changing Higgs boson Yukawa couplings | lambda[tc]^H |^2 < 6.9E-3 and | lambda[tu]^H |^2 < 9.8E-3.
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search for flavor changing Neutral Currents in top quark decays t to zq in pp collisions at sqrt s 8 tev
Physical Review Letters, 2014Co-Authors: S Chatrchyan, V Khachatryan, A M Sirunyan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Ero, C Fabjan, M FriedlAbstract:A search for flavor-changing Neutral Currents in top-quark decays t to Zq is performed in events produced from the decay chain t t-bar to Zq+Wb, where both vector bosons decay leptonically, producing a final state with three leptons (electrons or muons). A dataset collected with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 19.7 inverse femtobarns of proton-proton collisions at a center-of-mass energy of 8 TeV. No excess is seen in the observed number of events relative to the standard model prediction; thus no evidence for flavor-changing Neutral Currents in top-quark decays is found. A combination with a previous search at 7 TeV excludes a t to Zq branching fraction greater than 0.05% at the 95% confidence level.
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search for flavor changing Neutral Currents in top quark decays in pp collisions at 7 tev
Physics Letters B, 2013Co-Authors: S Chatrchyan, V Khachatryan, A M Sirunyan, A Tumasyan, W Adam, E Aguilo, T Bergauer, M Dragicevic, J Ero, C FabjanAbstract:The results of a search for flavor changing Neutral Currents in top quark decays t→Zqt→Zq in events with a topology compatible with the decay chain View the MathML sourcett¯→Wb+Zq→lνb+llq are presented. The search is performed with a data sample corresponding to an integrated luminosity of 5.0 fb−15.0 fb−1 of proton–proton collisions at a center-of-mass energy of 7 TeV, collected with the CMS detector at the LHC. The observed number of events agrees with the standard model prediction and no evidence for flavor changing Neutral Currents in top quark decays is found. A t→Zqt→Zq branching fraction greater than 0.21% is excluded at the 95% confidence level.
C Fabjan - One of the best experts on this subject based on the ideXlab platform.
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search for flavor changing Neutral Currents in top quark decays t to zq in pp collisions at sqrt s 8 tev
Physical Review Letters, 2014Co-Authors: S Chatrchyan, V Khachatryan, A M Sirunyan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Ero, C Fabjan, M FriedlAbstract:A search for flavor-changing Neutral Currents in top-quark decays t to Zq is performed in events produced from the decay chain t t-bar to Zq+Wb, where both vector bosons decay leptonically, producing a final state with three leptons (electrons or muons). A dataset collected with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 19.7 inverse femtobarns of proton-proton collisions at a center-of-mass energy of 8 TeV. No excess is seen in the observed number of events relative to the standard model prediction; thus no evidence for flavor-changing Neutral Currents in top-quark decays is found. A combination with a previous search at 7 TeV excludes a t to Zq branching fraction greater than 0.05% at the 95% confidence level.
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search for flavor changing Neutral Currents in top quark decays in pp collisions at 7 tev
Physics Letters B, 2013Co-Authors: S Chatrchyan, V Khachatryan, A M Sirunyan, A Tumasyan, W Adam, E Aguilo, T Bergauer, M Dragicevic, J Ero, C FabjanAbstract:The results of a search for flavor changing Neutral Currents in top quark decays t→Zqt→Zq in events with a topology compatible with the decay chain View the MathML sourcett¯→Wb+Zq→lνb+llq are presented. The search is performed with a data sample corresponding to an integrated luminosity of 5.0 fb−15.0 fb−1 of proton–proton collisions at a center-of-mass energy of 7 TeV, collected with the CMS detector at the LHC. The observed number of events agrees with the standard model prediction and no evidence for flavor changing Neutral Currents in top quark decays is found. A t→Zqt→Zq branching fraction greater than 0.21% is excluded at the 95% confidence level.