Measurement of the single-top-quark t-channel cross section in pp collisions at sqrt(s)=7 TeV using a multivariate analysis

Electroweak top-quark production offers a unique access to search for new physics phenomena. The measurement of the $t$-channel cross section allows to determine the Cabibbo-Kobayashi-Maskawa matrix element $IV_{\mathrm{tb}}I$ with high precision and without assuming its unitarity. We present the precise measurement of the $t$-channel single-top-quark production cross section with a multivariate analysis. Data collected with the CMS experiment in proton-proton collisions at a center-of-mass energy of $7$~\TeV, corresponding to 1.17~\fbinv for muon final states and 1.56~\fbinv for electron final states, are used for this measurement. The measured $t$-channel single-top-quark production cross section is $67.2\pm 6.1~\mathrm{pb}$, compatible with the approximate next-to-next-to-leading-order Standard Model prediction. The CKM matrix element $IV_{\mathrm{tb}}I$ is measured to be $1.020 \pm 0.046\text{ (meas.)} \pm 0.017\text{ (theor.)}$.