Study of heavy-flavor quarks produced in association with top-quark pairs at s √ =7 TeV using the ATLAS detector
Data(s) |
2014
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Resumo |
Using a sample of dilepton top-quark pair (tt ¯ ) candidate events, a study is performed of the production of top-quark pairs together with heavy-flavor (HF) quarks, the sum of tt ¯ +b+X and tt ¯ +c+X , collectively referred to as tt ¯ + HF . The data set used corresponds to an integrated luminosity of 4.7 fb −1 of proton-proton collisions at a center-of-mass energy of 7 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. The presence of additional HF (b or c ) quarks in the tt ¯ sample is inferred by looking for events with at least three b -tagged jets, where two are attributed to the b quarks from the tt ¯ decays and the third to additional HF production. The dominant background to tt ¯ + HF in this sample is tt ¯ +jet events in which a light-flavor jet is misidentified as a heavy-flavor jet. To determine the heavy- and light-flavor content of the additional b -tagged jets, a fit to the vertex mass distribution of b -tagged jets in the sample is performed. The result of the fit shows that 79 ± 14 (stat) ± 22 (syst) of the 105 selected extra b -tagged jets originate from HF quarks, 3 standard deviations away from the hypothesis of zero tt ¯ + HF production. The result for extra HF production is quoted as a ratio (R HF ) of the cross section for tt ¯ + HF production to the cross section for tt ¯ production with at least one additional jet. Both cross sections are measured in a fiducial kinematic region within the ATLAS acceptance. R HF is measured to be [6.2±1.1(stat)±1.8(syst)]% for jets with p T >25 GeV and |η|<2.5 , in agreement with the expectations from Monte Carlo generators. |
Formato |
application/pdf |
Identificador |
http://boris.unibe.ch/68735/1/PhysRevD.89072012.pdf Agustoni, Marco; Ancu, Lucian; Battaglia, Andreas; Beck, Hans Peter; Borer, Claudia; Cervelli, Alberto; Ereditato, Antonio; Fonseca, Maria; Gallo, Valentina; Haug, Sigve; Kruker, Tobias; Marti, Lukas; Schneider, Basil; Sciacca, Gianfranco; Weber, Michael (2014). Study of heavy-flavor quarks produced in association with top-quark pairs at s √ =7 TeV using the ATLAS detector. Physical review. D - particles, fields, gravitation, and cosmology, D89(7), 072012. Melville, N.Y.: American Physical Society 10.1103/PhysRevD.89.072012 <http://dx.doi.org/10.1103/PhysRevD.89.072012> doi:10.7892/boris.68735 info:doi:10.1103/PhysRevD.89.072012 urn:issn:1550-7998 |
Idioma(s) |
eng |
Publicador |
American Physical Society |
Relação |
http://boris.unibe.ch/68735/ |
Direitos |
info:eu-repo/semantics/openAccess |
Fonte |
Agustoni, Marco; Ancu, Lucian; Battaglia, Andreas; Beck, Hans Peter; Borer, Claudia; Cervelli, Alberto; Ereditato, Antonio; Fonseca, Maria; Gallo, Valentina; Haug, Sigve; Kruker, Tobias; Marti, Lukas; Schneider, Basil; Sciacca, Gianfranco; Weber, Michael (2014). Study of heavy-flavor quarks produced in association with top-quark pairs at s √ =7 TeV using the ATLAS detector. Physical review. D - particles, fields, gravitation, and cosmology, D89(7), 072012. Melville, N.Y.: American Physical Society 10.1103/PhysRevD.89.072012 <http://dx.doi.org/10.1103/PhysRevD.89.072012> |
Palavras-Chave | #530 Physics |
Tipo |
info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion PeerReviewed |