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

This paper describes the first measurement of the cross section of single top quark production in the $t$ channel in pp collision data at $\sqrt{s}=7$ TeV, recorded at LHC with the CMS detector with an integrated luminosity of 35.9 pb$^{-1}$. Leptonic decay channels with an electron or a muon in the final state are considered. After a selection optimized for the $t$-channel mode, two different and complementary analyses have been performed. The first analysis exploits the peculiar angular properties of the signal with data-driven background estimates. The second approach is based on a multivariate analysis technique that probes the compatibility of the candidate events with the signal, profiting of the excellent agreement of the CMS simulation with the data. Both analyses confirm Tevatron's observation of single top, and their combination measures a cross section of $83.6 \pm 29.8 (stat.+syst.) \pm 3.3 (lumi.) \,\, \text{pb}$ which is consistent with the Standard Model prediction.