Inclusive top-antitop pair production cross section at 5.02 TeV with CMS

The top quark pair production cross section is measured in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data collected in 2017 by the CMS experiment at the LHC corresponding to an integrated luminosity of 304 pb$^{-1}$ are analyzed. The measurement is performed using events with one electron and one muon of opposite sign, and at least two jets. The measured cross section is found to be $\sigma_{\mathrm{t}\bar{\mathrm{t}}}~=~60.3~\pm5.0~\mathrm{(stat)}\pm2.8~\mathrm{(syst)}\pm0.9~\mathrm{(lumi)}$ pb. To reduce the statistical uncertainty, a combination with the result in the $\ell$+jets channel, based on 27.4 pb$^{-1}$ of data collected in 2015 at the same center-of-mass energy of 5.02 TeV, is then performed, obtaining a value of $\sigma_{\mathrm{t}\bar{\mathrm{t}}}~=~62.6~\pm4.1~\mathrm{(stat)}\pm3.0~\mathrm{(syst+lumi)}$ pb, with a total uncertainty of 7.9%, in agreement with the standard model.