Inclusive W/Z cross section at 8 TeV

A measurement of inclusive W and Z production cross sections in pp collisions at $\sqrt{s}=8$~TeV is presented. Electron and muon final states are analyzed in a data sample collected with the CMS detector corresponding to an integrated luminosity $18.7 \pm 0.9\, \mathrm{pb}^{-1}$. The measured inclusive cross sections are $\sigma(\mathrm{pp} \rightarrow \mathrm{W}X) \times {\cal B}(\mathrm{W} \rightarrow \ell\nu ) = 11.88 \pm 0.03 ~\mathrm{(stat.)} \pm 0.22 ~\mathrm{(syst.)} \pm 0.52~\mathrm{(lumi.)}$~nb and $\sigma(\mathrm{pp} \rightarrow \mathrm{Z}X) \times {\cal B}(\mathrm{Z} \rightarrow \ell^+\ell^-) = 1.12 \pm 0.01 ~\mathrm{(stat.)} \pm 0.02 ~\mathrm{(syst.)} \pm 0.05 ~\mathrm{(lumi.)}$~nb, limited to a dilepton mass range of 60 to 120~GeV. The measured values agree with next-to-next-to-leading order QCD cross-section calculations.