Measurement of single top production in pp collisions at 7 TeV with the CMS detector

We report on the first measurement of the single top t-channel production cross section in proton-proton collisions at center of mass energy $\sqrt{s}$ = 7 TeV with the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC), performed with an integrated luminosity of 36 $pb^{-1}$ . Final states where the top decays leptonically through the chains $t \rightarrow Wb \rightarrow lb \nu$ are considered, and the full four momentum of the top quark is reconstructed from its decay products. Two complementary analyses are performed: a robust template fit analysis aiming to be model-independent based on the fit to a two variables distribution, and a multivariate analysis aiming to maximize the sensitivity of the measurement using a boosted decision tree discriminant. The measurements of the two analyses are then combined, and a lower bound on module of the Cabibbo Kobayashi Maskawa matrix element $V_{tb}$ is extracted. The measured cross section is $83.6 \pm 29.8$ $pb$ and it is consistent with the standard model expectations, resulting in a lower bound of \textsf{I}$V_{tb}$\textsf{I} $ > 0.68$ at $95\%$ confidence level