  Evidence is presented for the associated production of a single top quark and
W boson in pp collisions at sqrt(s) = 7 TeV with the CMS experiment at the LHC.
The analyzed data corresponds to an integrated luminosity of 4.9 inverse
femtobarns. The measurement is performed using events with two leptons and a
jet originated from a b quark. A multivariate analysis based on kinematic
properties is utilized to separate the t t-bar background from the signal. The
observed signal has a significance of 4.0 sigma and corresponds to a cross
section of 16 +5 -4 pb, in agreement with the standard model expectation of
15.6 +/-0.4 +1.0 -1.2 pb.
