Measurement of the inclusive $\mathrm{t\bar{t}}$ cross section in final states with at least one lepton and additional jets with 302 pb$^{-1}$ of pp collisions at $\sqrt{s}$ = 5.02 TeV

Abstract

A measurement of the top quark pair ($\mathrm{t\bar{t}}$) production cross section in proton-proton collisions at a centre-of-mass energy of 5.02 TeV is presented. The data were collected at the LHC in autumn 2017, in dedicated runs with low-energy and low-intensity conditions with respect to the default configuration, and correspond to an integrated luminosity of 302 pb$^{-1}$. The measurement is performed using events with one electron or muon, and multiple jets, at least one of them being identified as originating from a b quark (b tagged). Events are classified based on the number of all reconstructed jets and of b-tagged jets. Multivariate analysis techniques are used to enhance the separation between the signal and backgrounds. The measured cross section is 62.5 $\pm$ 1.6 (stat) $^{+2.6}_{-2.5}$ (syst) $\pm$ 1.2 (lumi) pb. A combination with the result in the dilepton channel based on the same data set yields a value of 62.3 $\pm$ 1.5 (stat) $\pm$ 2.4 (syst) $\pm$ 1.2 (lumi) pb, to be compared with the standard model prediction of 69.5 $^{+3.5}_{-3.7}$ pb at next-to-next-to-leading order in perturbative quantum chromodynamics.