CMS collaboration (2230 authors)Nayak, ArunaBargassa, PedrameBeirão Da Cruz E Silva, CristóvãoCalpas, BettyDi Francesco, AgostinoFaccioli, PietroFerreira Parracho, Pedro GuilhermeGallinaro, MicheleHollar, JonathanLeonardo, NunoLloret Iglesias, LaraRodrigues Antunes, JoaoSeixas, JoaoToldaiev, OleksiiVadruccio, DanieleVarela, JoaoVischia, PietroDavid Tinoco Mendes, AndreSilva, PedroMusella, PasqualePela, Joao2019-02-042019-02-042017-10-02http://dx.doi.org/10.1007/JHEP10(2017)006http://hdl.handle.net/10400.26/27369A measurement of the cross section for top quark-antiquark ( $ \mathrm{t}\overline{\mathrm{t}} $ ) pairs produced in association with a photon in proton-proton collisions at $ \sqrt{s}=8 $ TeV is presented. The analysis uses data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.7 fb$^{1}$. The signal is defined as the production of a $ \mathrm{t}\overline{\mathrm{t}} $ pair in association with a photon having a transverse energy larger than 25 GeV and an absolute pseudorapidity smaller than 1.44. The measurement is performed in the fiducial phase space corresponding to the semileptonic decay chain of the $ \mathrm{t}\overline{\mathrm{t}} $ pair, and the cross section is measured relative to the inclusive $ \mathrm{t}\overline{\mathrm{t}} $ pair production cross section. The fiducial cross section for associated $ \mathrm{t}\overline{\mathrm{t}} $ pair and photon production is found to be 127 ±27 (stat+syst) fb per semileptonic final state. The measured value is in agreement with the theoretical prediction.engjournal article2019-02-04