@Article{ATLASCollaborationAad_etal2015,
author="ATLAS Collaboration (Aad, G. et al
and Cabrera Urban, S.
and Castillo Gimenez, V.
and Costa, M. J.
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 King, M.
and Lacasta, C.
and Lacuesta, V. R.
and Marti-Garcia, S.
and Mitsou, V. A.
and Moles-Valls, R.
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 Vos, M.",
title="Observation of top-quark pair production in association with a photon and measurement of the t(t)over-bar gamma production cross section in pp collisions at root s=7 TeV using the ATLAS detector",
journal="Physical Review D",
year="2015",
publisher="Amer Physical Soc",
volume="91",
number="7",
pages="072007--28pp",
abstract="A search is performed for top-quark pairs (t (t) over bar) produced together with a photon (gamma) with transverse energy greater than 20 GeV using a sample of t (t) over bar candidate events in final states with jets, missing transverse momentum, and one isolated electron or muon. The data set used corresponds to an integrated luminosity of 4.59 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. In total, 140 and 222 t (t) over bar gamma candidate events are observed in the electron and muon channels, to be compared to the expectation of 79 +/- 26 and 120 +/- 39 non-t (t) over bar gamma background events, respectively. The production of t (t) over bar gamma events is observed with a significance of 5.3 standard deviations away from the null hypothesis. The t (t) over bar gamma production cross section times the branching ratio (BR) of the single-lepton decay channel is measured in a fiducial kinematic region within the ATLAS acceptance. The measured value is sigma(fid)(t (t) over bar gamma) x BR = 63 +/- 8(stat)(-13)(+17) (syst) +/- 1(lumi) fb per lepton flavor, in good agreement with the leading-order theoretical calculation normalized to the next-to-leading-order theoretical prediction of 48 +/- 10 fb.",
optnote="WOS:000353545500001",
optnote="exported from refbase (https://references.ific.uv.es/refbase/show.php?record=2215), last updated on Thu, 21 May 2015 15:38:34 +0000",
issn="1550-7998",
doi="10.1103/PhysRevD.91.072007",
opturl="http://arxiv.org/abs/1502.00586",
opturl="https://doi.org/10.1103/PhysRevD.91.072007",
archivePrefix="arXiv",
eprint="1502.00586",
language="English"
}