Measurement of the inclusive and differential $\text{t}\bar{\text{t}}\gamma$ cross section and EFT interpretation in the dilepton channel at $\sqrt{s}=13\,\text{TeV}$

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 $138\,\text{fb}^{-1}$ was recorded by the CMS experiment at $\sqrt{s}=13\,\text{TeV}$ 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 $174.4\pm2.5\,\text{(stat)}\pm 6.1\,\text{(syst)}\,\text{fb}$ is measured in a signal region with at least one b-tagged jet and exactly one photon with transverse momentum above $20\,\text{GeV}$. 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.