@Article{ATLASCollaborationAad_etal2014,
author="ATLAS Collaboration (Aad, G. et al
and Cabrera Urban, S.
and Castillo Gimenez, V.
and Costa, M. J.
and Fassi, F.
and Ferrer, A.
and Fiorini, L.
and Fuster, J.
and Garcia, C.
and Garcia Navarro, J. E.
and Gonzalez de la Hoz, S.
and Hernandez Jimenez, Y.
and Higon-Rodriguez, E.
and Irles Quiles, A.
and Kaci, M.
and Lacasta, C.
and Lacuesta, V. R.
and March, L.
and Marti-Garcia, S.
and Mi{\~A}{\textpm}ano, M.
and Mitsou, V. A.
and Moles-Valls, R.
and Moreno Llacer, M.
and Oliver Garcia, E.
and Pedraza Lopez, S.
and Perez Garcia-Esta{\~A}{\textpm}, M. T.
and Romero Adam, E.
and Ros, E.
and Salt, J.
and Sanchez Martinez, V.
and Soldevila, U.
and Sanchez, J.
and Torro Pastor, E.
and Valero, A.
and Valladolid Gallego, E.
and Valls Ferrer, J. A.
and Villaplana Perez, M.
and Vos, M.",
title="Study of heavy-flavor quarks produced in association with top-quark pairs at root s=7 TeV using the ATLAS detector",
journal="Physical Review D",
year="2014",
publisher="Amer Physical Soc",
volume="89",
number="7",
pages="072012--23pp",
abstract="Using a sample of dilepton top-quark pair ((tt) over bar) candidate events, a study is performed of the production of top-quark pairs together with heavy-flavor (HF) quarks, the sum of (tt) over bar + b + X and (tt) over bar + c + X, collectively referred to as (tt) over bar + 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) over bar 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) over bar decays and the third to additional HF production. The dominant background to (tt) over bar + HF in this sample is (tt) over bar + 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) over bar + HF production. The result for extra HF production is quoted as a ratio (R-HF) of the cross section for (tt) over bar + HF production to the cross section for (tt) over bar 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 vertical bar eta vertical bar < 2.5, in agreement with the expectations from Monte Carlo generators.",
optnote="WOS:000335235200001",
optnote="exported from refbase (https://references.ific.uv.es/refbase/show.php?record=1779), last updated on Sun, 01 Jun 2014 15:45:32 +0000",
issn="1550-7998",
doi="10.1103/PhysRevD.89.072012",
opturl="http://arxiv.org/abs/1304.6386",
opturl="https://doi.org/10.1103/PhysRevD.89.072012",
archivePrefix="arXiv",
eprint="1304.6386",
language="English"
}