Measurement of the single top quark and antiquark production cross sections in the t channel and their ratio in pp collisions at sqrt(s)=13 TeV

The cross sections for the production of single top quarks and antiquarks in the $t$ channel, and their ratio, are measured in proton-proton collisions at a center-of-mass energy of $13~\mathrm{TeV}$. The full data set recorded in 2016 by the CMS detector at the LHC is analyzed, corresponding to an integrated luminosity of $35.9~\mathrm{fb}^{-1}$. Events with one muon or electron and two jets are selected, where one of the two jets is identified as originating from a bottom quark. A multivariate discriminator exploiting several kinematic variables is applied to separate signal from background events. The ratio $R_{t\mathrm{\text{-}ch.}}$ of the cross sections is measured to be $1.65 \pm0.02\,\text{(stat)} \pm0.04\,\text{(syst)}$. The total cross section for the production of single top quarks or antiquarks is measured to be $219.0 \pm1.5\,\text{(stat)} \pm33.0\,\text{(syst)} \,\mathrm{pb}$ and the absolute value of the CKM matrix element $V_{\mathrm{tb}}$ is determined to be $1.00 \pm0.05\,\text{(exp)} \pm0.02 \,\text{(theo)}$. All results are in agreement with the standard model predictions.