  The transverse momentum spectra of weak vector bosons are measured in the CMS
experiment at the LHC. The measurement uses a sample of proton-proton
collisions at sqrt(s) = 8 TeV, collected during a special low-luminosity
running that corresponds to an integrated luminosity of 18.4 +/- 0.5 inverse
picobarns. The production of W bosons is studied in both electron and muon
decay modes, while the production of Z bosons is studied using only the dimuon
decay channel. The ratios of W- to W+ and Z to W differential cross sections
are also measured. The measured differential cross sections and ratios are
compared with theoretical predictions up to next-to-next leading order in QCD.
