Search for anomalous Wtb couplings and top FCNC in t-channel single-top-quark events in the CMS experiment

Single-top-quark events in the t-channel are used to probe Wtb anomalous couplings and to search for top-quark Flavor-Changing Neutral Current (FCNC) interactions in proton-proton collisions with the CMS experiment. A Bayesian neural network is used to discriminate between signal and backgrounds. The observed event yields are consistent with SM prediction, and exclusion limits at 95\% C.L. are determined

Measurement of the tt¯ production cross section in the dilepton channel in pp collisions at s√ = 8 TeV

The top-antitop quark ( tt¯ ) production cross section is measured in proton-proton collisions at s√ = 8 TeV with the CMS experiment at the LHC, using a data sample corresponding to an integrated luminosity of 5.3 fb−1. The measurement is performed by analysing events with a pair of electrons or muons, or one electron and one muon, and at least two jets, one of which is identified as originating from hadronisation of a bottom quark. The measured cross section is 239 ± 2 (stat.) ± 11 (syst.) ± 6 (lum.) pb, for an assumed top-quark mass of 172.5 GeV, in agreement with the prediction of the standard model

Observation of the associated production of a single top quark and a W boson in pp collisions at s\sqrt{s} = 8 TeV

The first observation of the associated production of a single top quark and a $W$ boson is presented. The analysis is based on a data set corresponding to an integrated luminosity of $12.2\text{}\text{}{\mathrm{fb}}^{-1}$ of proton-proton collisions at $\sqrt{s}=8\text{}\text{}\mathrm{TeV}$ recorded by the CMS experiment at the LHC. Events with two leptons and a jet originating from a $b$ quark are selected. A multivariate analysis based on kinematic and topological properties is used to separate the signal from the dominant $t\overline{t}$ background. An excess consistent with the signal hypothesis is observed, with a significance which corresponds to 6.1 standard deviations above a background-only hypothesis. The measured production cross section is $23.4±5.4\text{}\text{}\text{pb}$, in agreement with the standard model prediction