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Compact Muon Solenoid
LHC, CERN

CMS-PAS-TOP-21-004
Measurement of the inclusive and differential $\mathrm{t\bar{t}}\gamma$ cross section and EFT interpretation in the dilepton channel at $\sqrt{s}=$ 13 TeV
Abstract: The production cross section of a top quark pair in association with a photon is measured in pp collisions in the decay channel with two oppositely charged leptons ($\text{e}^\pm\mu^\mp$, $\text{e}^+\text{e}^-$, $\mu^+\mu^-$). The data set of 138 fb$^{-1}$ was recorded by the CMS experiment at $\sqrt{s}=$ 13 TeV during the 2016 to 2018 data-taking period of the CERN LHC. A fiducial phase space is defined such that photons radiated by initial-state particles, top quarks, or any of their decay products are included. An inclusive cross section of 174.4 $\pm$ 2.5 (stat) $\pm$ 6.1 (syst) fb is measured in a signal region with at least one b-tagged jet and exactly one photon with transverse momentum above 20 GeV. Differential cross sections are measured as a function of several kinematic observables of the photon, leptons, and jet, and compared to standard model predictions. The measurements are also interpreted in the standard model effective field theory framework, and limits on the relevant Wilson coefficients are combined with a previous CMS measurement of the same production process using single-lepton events.
CMS Publications
Compact Muon Solenoid
LHC, CERN