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.
Categories: hep-ex
