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10.1103-PhysRevD.89.072012.pdf (525.79 kB)

Study of heavy-flavor quarks produced in association with top-quark pairs at vs = 7??TeV using the ATLAS detector

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posted on 2023-06-09, 06:02 authored by Benedict AllbrookeBenedict Allbrooke, Lily AsquithLily Asquith, Alessandro CerriAlessandro Cerri, C A Chavez Barajas, Antonella De SantoAntonella De Santo, Fabrizio SalvatoreFabrizio Salvatore, I Santoyo Castillo, K Suruliz, Mark SuttonMark Sutton, Iacopo Vivarelli, The ATLAS Collaboration
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 (RHF) of the cross section for t¯t?+?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. RHF is measured to be [6.2±1.1(stat)±1.8(syst)]% for jets with pT>25??GeV and |?|<2.5, in agreement with the expectations from Monte Carlo generators.

Funding

ATLAS; G0275; STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL; ST/I006048/1

History

Publication status

  • Published

File Version

  • Published version

Journal

Physical Review D

ISSN

2470-0010

Publisher

American Physical Society

Issue

7

Volume

89

Page range

072012

Department affiliated with

  • Physics and Astronomy Publications

Research groups affiliated with

  • Experimental Particle Physics Research Group Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2017-05-02

First Open Access (FOA) Date

2017-05-02

First Compliant Deposit (FCD) Date

2017-05-02

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