Measurement of W-helicity fractions in single top events topology

We present a measurement of the W-boson helicity fractions in single-top events topology in muon+jets final state using LHC $pp$ collisions at $7\,\rm TeV$ and $8\,\rm TeV$ center-of-mass energies. The datasets are collected by the CMS detector during 2011 (A) and 2012 (A+B) runs, respectively corresponding to an integrated luminosity of $1.14\,\rm fb^{-1}$ and $5.3\rm\,fb^{-1}$. The combination of the two measurements yields $\rm F_L=0.293\pm0.069(\rm{stat.})\pm 0.030(\rm{syst.}), F_0=0.713\pm0.114(\rm{stat.})\pm 0.023(\rm{syst.})$ and $F_R=-0.006\pm0.057(\rm{stat.})\pm 0.027(\rm{syst.}).$ The measured polarizations are used to set limits on $tWb$ anomalous couplings.