Measurements of single top quark cross sections in pp collisions at 8 TeV with the CMS detector

Measurements are presented of the single top quark production in proton-proton collisions at the LHC at a centre-of-mass energy of 8 TeV, using data collected with the CMS experiment during 2012. The first analysis, in the t-channel single top production mode, considers decay channels where the W comes from the top decays into electron-neutrino or muon-neutrino. It makes use of a template fit exploiting the pseudorapidity distribution of the recoil jet and the reconstructed top quark mass, using background estimates determined from control samples in data. The measurement of top/antitop cross section ratio is also presented. The second analysis, measuring the associated production cross section of single top quark and W boson, considers final states in which the associated W boson, as well as the one originating from the top quark, decay leptonically. Multivariate methods are used to separate the signal from the topologically similar top pair production background. Multivariate techniques are also adopted in the search for s-channel single top quark production finally reported, in order to discriminate the very small signal from the huge background processes.