Measurement of the t t ¯ production cross section, the top quark mass, and the strong coupling constant using dilepton events in pp collisions at s = 13 Te

Abstract

A measurement of the top quark-antiquark pair production cross section ${\sigma }_{t\overline{t}}$ in proton-proton collisions at a centre-of-mass energy of 13 $\text{Te}$ is presented. The data correspond to an integrated luminosity of $35.9{\text{fb}}^{-1}$ , recorded by the CMS experiment at the CERN LHC in 2016. Dilepton events ( $e$ ${}^{\pm }$ $\mu$ ${}^{\mp }$ , ${\mu }^{+}{\mu }^{-}$ , $e^{+}{e}^{-}$ ) are selected and the cross section is measured from a likelihood fit. For a top quark mass parameter in the simulation of $m_t^{\mathrm{MC}}=172.5\text{Ge}$ the fit yields a measured cross section ${\sigma }_{t\overline{t}}=803\pm 2\text{(stat)}\pm 25\text{(syst)}\pm 20\text{(lumi)}\text{pb}$ , in agreement with the expectation from the standard model calculation at next-to-next-to-leading order. A simultaneous fit of the cross section and the top quark mass parameter in the powheg simulation is performed. The measured value of $m_t^{\mathrm{MC}}=172.33\pm 0.14\text{(stat)}{}_{-0.72}^{+0.66}\text{(syst)}\text{Ge}$ is in good agreement with previous measurements. The resulting cross section is used, together with the theoretical prediction, to determine the top quark mass and to extract a value of the strong coupling constant with different sets of parton distribution functions.