Studies of tt+V at CMS

A measurement of the production cross-section of a pair of top quarks in association with a photon, using 19.7 $fb^{-1}$ of pp collision data collected by CMS detector at $\sqrt{s} = $ 8 TeV, and with W and Z boson, using 12.9 $fb^{-1}$ of data collected at $\sqrt{s} = $ 13 TeV, is presented. The measurement of t$\bar{\text{t}}\gamma$ is performed in in the fiducial phase space corresponding to the semileptonic decay chain of the top quark pair, and the cross section is measured relative to the inclusive top quark pair production cross section. The fiducial cross section for this process is found to be $\sigma_{\text{t}\bar{\text{t}}\gamma}^{fid} = $ 127 $\pm $ 27 (stat + syst) fb. The measurement of t$\bar{\text{t}}$W and t$\bar{\text{t}}$Z processes combines three final states with two same-sign, three and four leptons. The $\mathrm{t\overline{t}W}$ and $\mathrm{t\overline{t}Z}$ production cross sections are measured to be $\sigma(\mathrm{t\overline{t}Z})=0.70^{+0.16}_{-0.15}(\text{stat.})^{+0.14}_{-0. 12}(\text{sys.})$ pb and$\sigma(\mathrm{t\overline{t}W})=0.98~^{+0.23}_{-0.22}(\text{stat.})~^{+0.22}_{-0.18}(\text{sys.})$ pb with an expected (observed) significance of 2.6 (3.9) and 5.8 (4.6) standard deviations from the background-only hypothesis respectively. The measured cross sections are in agreement with the standard model prediction.