# Quark Matter 2014 - XXIV International Conference on Ultrarelativistic Nucleus-Nucleus Collisions

19-24 May 2014
Europe/Zurich timezone

## Z and W production in pp, pPb and PbPb collisions with CMS

19 May 2014, 17:10
20m

### helium

Contributed Talk Electromagnetic Probes

### Speaker

Anna Zsigmond (Wigner RCP, Budapest (HU))

### Description

The weak bosons, Z and W, do not participate in the strong interaction, and thus constitute clean probes of the initial state of nuclear collisions. Detected trough their leptonic decay channels, they provide constraints on the nuclear parton distribution functions (PDF). In particular the W boson proves a unique constraint on the sea quark distributions. We report on CMS measurements of weak boson production in pp, pPb and PbPb. Particular emphasis is place on measurements of the 35 nb$^{-1}$ of pPb data collected at the beginning of 2013. This provides access to a Bjorken x region, $10^{-3}$ -- 1, which is lacking precision experimental measurements needed by nuclear PDF parametrizations. The Z boson nuclear modification factors as a function of transverse momentum and rapidity will be shown, together with forward to backward ratios. The W boson yields, charge asymmetries, and forward to backward ratios in pPb collisions will also be reported. With a production cross section an order of magnitude larger than the Z, the W allows precise comparisons to theoretical predictions. Comparisons to PDFs are made for both Z and W measurements
On behalf of collaboration: CMS

### Primary author

Anna Zsigmond (Wigner RCP, Budapest (HU))

 Slides