Electroweak boson production in PbPb collisions with CMS

Electroweak gauge bosons W and Z, do not interact strongly, and thus constitute clean probes of the initial state of nucleus-nucleus collisions. The comparison of their production cross-sections in pp and in nuclear collisions provides an estimate of the nuclear parton distribution functions. Despite the low production cross section of weak bosons compared to other nuclear processes, the relatively clean signal of their leptonic decay channel allows their detection. This paper reports measurements of Z and W bosons, produced in PbPb and pp collisions at nucleon-nucleon center of mass energy $\sqrt{s}$ = 2.76 TeV with the CMS detector. The Z boson yield and the nuclear modification factor (R$_{AA}$) corresponding to the integrated luminosity of 150 $\mu$b$^{-1}$ are presented. The search for W bosons has been performed in the muon plus neutrino channel, using the data sample with integrated luminosity of 7.2 $\mu$b$^{-1}$. Event centrality an muon pseudorapidity dependencies are studied for the complete W candidate sample as well as samples separated by charge (W$^+$ and W$^-$).