Çetin, Serkant Ali2020-11-192020-11-192017-11-15https://hdl.handle.net/11411/2682https://doi.org/10.1007/JHEP11(2017)086The cross section of a top-quark pair produced in association with a photon is measured in proton-proton collisions at a centre-of-mass energy of root s = 8 TeV with 20.2 fb(-1) of data collected by the ATLAS detector at the Large Hadron Collider in 2012. The measurement is performed by selecting events that contain a photon with transverse momentum p(T) > 15 GeV, an isolated lepton with large transverse momentum, large missing transverse momentum, and at least four jets, where at least one is identified as originating from a b-quark. The production cross section is measured in a fiducial region close to the selection requirements. It is found to be 139 +/- 7 (stat.) +/- 17 (syst.) fb, in good agreement with the theoretical prediction at next-to-leading order of 151 +/- 24 fb. In addition, differential cross sections in the fiducial region are measured as a function of the transverse momentum and pseudorapidity of the photon.eninfo:eu-repo/semantics/openAccessHadron-Hadron scattering (experiments)Top physicsArticle2-s2.0-8503574532510.1007/JHEP11(2017)086Q1Q1WOS:000415660000002