Observation of associated production of a single top quark and W boson at 8 TeV

The observation of the associated production of a single top quark and W boson using 12.2 fb$^{-1}$ of pp collisions at $\sqrt{s}$ = 8 TeV with the CMS experiment is presented. A multivariate analysis based on kinematic variables was used to discriminate signal from the dominant ttbar background. The observed signal has a significance of 6.0 $\sigma$ and a cross section of $23.9^{+5.7}_{-5.6}$ pb. A cut and count cross check analysis was also carried out, finding a signal with a significance of 3.6 sigma and a cross section of $33.9^{+8.6}_{-8.6}$ pb. The results are in agreement with the standard model expectation of $22.2\pm0.6\pm1.4$ pb.