TY - JOUR
T1 - Observation of top-quark pair production in association with a photon and measurement of the t t ¯ γ production cross section in pp collisions at √s =7 TeV using the ATLAS detector
AU - ATLAS Collaboration
AU - Aad, G.
AU - Abbott, B.
AU - Abdallah, J.
AU - Abdel Khalek, S.
AU - Abdinov, O.
AU - Aben, R.
AU - Abi, B.
AU - Abolins, M.
AU - Abouzeid, O. S.
AU - Abramowicz, H.
AU - Abreu, H.
AU - Abreu, R.
AU - Abulaiti, Y.
AU - Acharya, B. S.
AU - Adamczyk, L.
AU - Adams, D. L.
AU - Adelman, J.
AU - Adomeit, S.
AU - Adye, T.
AU - Agatonovic-Jovin, T.
AU - Aguilar-Saavedra, J. A.
AU - Agustoni, M.
AU - Ahlen, S. P.
AU - Ahmadov, F.
AU - Aielli, G.
AU - Akerstedt, H.
AU - Åkesson, T. P.A.
AU - Akimoto, G.
AU - Akimov, A. V.
AU - Alberghi, G. L.
AU - Albert, J.
AU - Albrand, S.
AU - Alconada Verzini, M. J.
AU - Aleksa, M.
AU - Aleksandrov, I. N.
AU - Alexa, C.
AU - Alexander, G.
AU - Alexandre, G.
AU - Alexopoulos, T.
AU - Alhroob, M.
AU - Alimonti, G.
AU - Alio, L.
AU - Alison, J.
AU - Allbrooke, B. M.M.
AU - Allison, L. J.
AU - Allport, P. P.
AU - Almond, J.
AU - Aloisio, A.
AU - Alonso, A.
AU - Yang, Y.
N1 - Publisher Copyright:
© 2015 CERN. © 2015 CERN, for the ATLAS Collaboration. Published by the American Physical Society under the terms of the »http://creativecommons.org/licenses/by/3.0/» Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
PY - 2015/4/28
Y1 - 2015/4/28
N2 - A search is performed for top-quark pairs (tt¯) produced together with a photon (γ) with transverse energy greater than 20 GeV using a sample of tt¯ 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 tt¯γ candidate events are observed in the electron and muon channels, to be compared to the expectation of 79±26 and 120±39 non-tt¯γ background events, respectively. The production of tt¯γ events is observed with a significance of 5.3 standard deviations away from the null hypothesis. The tt¯γ 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 σtt¯γfid×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.
AB - A search is performed for top-quark pairs (tt¯) produced together with a photon (γ) with transverse energy greater than 20 GeV using a sample of tt¯ 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 tt¯γ candidate events are observed in the electron and muon channels, to be compared to the expectation of 79±26 and 120±39 non-tt¯γ background events, respectively. The production of tt¯γ events is observed with a significance of 5.3 standard deviations away from the null hypothesis. The tt¯γ 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 σtt¯γfid×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.
UR - https://www.scopus.com/pages/publications/84929089097
UR - https://www.scopus.com/pages/publications/84929089097#tab=citedBy
U2 - 10.1103/PhysRevD.91.072007
DO - 10.1103/PhysRevD.91.072007
M3 - Article
AN - SCOPUS:84929089097
SN - 1550-7998
VL - 91
JO - Physical Review D - Particles, Fields, Gravitation and Cosmology
JF - Physical Review D - Particles, Fields, Gravitation and Cosmology
IS - 7
M1 - 072007
ER -