Measurement of the t-channel single-top-quark production cross section and of the |V(tb)| CKM matrix element in pp collisions at sqrt(s) = 8 TeV

Measurements are presented of the t-channel single-top-quark production cross section in proton-proton collisions at √s = 8 TeV. The results are based on a data sample corresponding to an integrated luminosity of 19.7 fb-1 recorded with the CMS detector at the LHC. The cross section is measured inclusively, as well as separately for top (t) and antitop ((t)over-bar) , in final states with a muon or an electron. The measured inclusive t-channel cross section is σ(t-ch.) = 83.6 +/- 2.3 (stat.) +/- 7.4 (syst.) pb. The single t and (t)over-bar cross sections are measured to be σ(t-ch.(t)) = 53.8 +/- 1.5 (stat.) +/- 4.4 (syst.) pb and σ(t-ch.((t)over-bar)) = 27.6 +/- 1.3 (stat.) +/- 3.7 (syst.) pb, respectively. The measured ratio of cross sections is R(t-ch.) = σ(t-ch.(t))/σ(t-ch.((t)over-bar)) = 1.95 +/- 0.10 (stat.) +/- 0.19 (syst.), in agreement with the standard model prediction. The modulus of the Cabibbo-Kobayashi-Maskawa matrix element V(tb) is extracted and, in combination with a previous CMS result at √s = 7 TeV, a value |V(tb)| = 0.998 +/- 0.038 (exp.) +/- 0.016 (theo.) is obtained.