  A first measurement of the cross section of single top quark production in
the t channel in pp collision at sqrt(s)=7 TeV is presented. The measurement is
performed on a data sample corresponding to an integrated luminosity of 35.9
pb^-1 recorded at the LHC with the CMS detector. 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. Both analyses confirm the Tevatron's observation of single top,
and their combination measures a cross section of sigma = 83.6 +/-
29.8(stat.+syst.) +/- 3.3 (lumi.) pb, which is consistent with the Standard
Model prediction.
