Measurement of the associated production of a W boson and a charm quark at $\sqrt{s}=8~\mathrm{TeV}$

A measurement of the associated production of a W boson and a charm quark is presented. The analysis uses a data sample corresponding to a total integrated luminosity of $19.7~\mathrm {fb}^{-1}$ collected by the CMS detector at the LHC at a centre-of-mass energy of 8 TeV. W bosons are identified through their leptonic decays to an electron or a muon and a neutrino. Charm jets are selected using semileptonic and other inclusive decays of charm hadrons. The cross section $\sigma({\rm pp} \rightarrow {\rm W + c + X}) {\cal B}({\rm W}\rightarrow \ell \nu)$ (where $\ell =$ e and $\mu$), and the cross section ratio $\sigma({\rm pp} \rightarrow {\rm W^+ + \bar{c} + X})/\sigma({\rm pp} \rightarrow {\rm W^- + c + X})$ are measured, both inclusively and differentially as a function of the absolute value of the pseudorapidity and the transverse momentum of the lepton from the W boson decay. The measurements are compared with theoretical predictions.