Cross section measurement of $t$-channel single top quark production in pp collisions at $\sqrt s =$ 13 TeV

The cross section for the production of single top quarks in the t channel is measured in proton–proton collisions at 13 TeV with the CMS detector at the LHC. The analyzed data correspond to an integrated luminosity of 2.2 fb−1 . The event selection requires one muon and two jets where one of the jets is identified as originating from a bottom quark. Several kinematic variables are then combined into a multivariate discriminator to distinguish signal from background events. A fit to the distribution of the discriminating variable yields a total cross section of 238±13(stat)±29(syst) pb and a ratio of top quark and top antiquark production of Rt-ch.=1.81±0.18(stat)±0.15(syst) . From the total cross section the absolute value of the CKM matrix element Vtb is calculated to be 1.05±0.07(exp)±0.02(theo) . All results are in agreement with the standard model predictions.