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

ATLAS Collaboration

doi:10.1103/PhysRevD.91.072007

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

ATLAS Collaboration

Aix-Marseille Université and CNRS/IN2P3
University of Oklahoma
Academia Sinica - Institute of Physics
Université Paris-Sud
Azerbaijan National Academy of Sciences
University of Amsterdam
Oklahoma State University
Michigan State University
University of Toronto
Tel Aviv University
Technion-Israel Institute of Technology
CERN
Stockholm University
Oskar Klein Centre
National Institute for Nuclear Physics
Abdus Salam International Centre for Theoretical Physics
King's College London
AGH University of Krakow
Brookhaven National Laboratory
Yale University
Ludwig Maximilian University of Munich
Rutherford Appleton Laboratory
University of Belgrade
Laboratório de Instrumentação e Física Experimental de Partículas
University of Granada
University of Bern
Boston University
Joint Institute for Nuclear Research
University of Rome Tor Vergata
Lund University
The University of Tokyo
RAS - P.N. Lebedev Physics Institute
University of Bologna
University of Victoria BC
Université Grenoble Alpes
Instituto de Física La Plata
Horia Hulubei National Institute of Physics and Nuclear Engineering
University of Geneva
National Technical University of Athens
University of Udine
The University of Chicago
University of Birmingham
Lancaster University
University of Liverpool
University of Manchester
University of Naples Federico II
University of Copenhagen
University of Glasgow

Research output: Contribution to journal › Article › peer-review

60 Citations (Scopus)

Abstract

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.

Original language	English
Article number	072007
Journal	Physical Review D - Particles, Fields, Gravitation and Cosmology
Volume	91
Issue number	7
DOIs	https://doi.org/10.1103/PhysRevD.91.072007
Publication status	Published - 28 Apr 2015
Externally published	Yes

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10.1103/PhysRevD.91.072007

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@article{02455ff18c694a2891673a76c4947cad,

title = "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",

abstract = "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.",

author = "\{ATLAS Collaboration\} and G. Aad and B. Abbott and J. Abdallah and \{Abdel Khalek\}, S. and O. Abdinov and R. Aben and B. Abi and M. Abolins and Abouzeid, \{O. S.\} and H. Abramowicz and H. Abreu and R. Abreu and Y. Abulaiti and Acharya, \{B. S.\} and L. Adamczyk and Adams, \{D. L.\} and J. Adelman and S. Adomeit and T. Adye and T. Agatonovic-Jovin and Aguilar-Saavedra, \{J. A.\} and M. Agustoni and Ahlen, \{S. P.\} and F. Ahmadov and G. Aielli and H. Akerstedt and {\AA}kesson, \{T. P.A.\} and G. Akimoto and Akimov, \{A. V.\} and Alberghi, \{G. L.\} and J. Albert and S. Albrand and \{Alconada Verzini\}, \{M. J.\} and M. Aleksa and Aleksandrov, \{I. N.\} and C. Alexa and G. Alexander and G. Alexandre and T. Alexopoulos and M. Alhroob and G. Alimonti and L. Alio and J. Alison and Allbrooke, \{B. M.M.\} and Allison, \{L. J.\} and Allport, \{P. P.\} and J. Almond and A. Aloisio and A. Alonso and A. Moraes",

note = "Publisher Copyright: {\textcopyright} 2015 CERN. {\textcopyright} 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.",

year = "2015",

month = apr,

day = "28",

doi = "10.1103/PhysRevD.91.072007",

language = "English",

volume = "91",

journal = "Physical Review D - Particles, Fields, Gravitation and Cosmology",

issn = "1550-7998",

number = "7",

}

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. / ATLAS Collaboration.
In: Physical Review D - Particles, Fields, Gravitation and Cosmology, Vol. 91, No. 7, 072007, 28.04.2015.

Research output: Contribution to journal › Article › peer-review

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 - Moraes, A.

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

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 -

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

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