W/Z Production at ATLAS

The W and Z bosons are produced at LHC with high cross-sections and are the most copious sources of high-pt leptons. These two characteristics make them suitable for many purposes, from the very first stages of the data taking up to the high luminosity scenarios. In particular Z to lepton pairs events allow to determine lepton trigger and reconstruction efficiencies as well as resolutions and relative alignment. Then W and Z cross-sections measurement is one of the first benchmarks to have a complete and detailed understanding of the known Standard Model physics in new experimental conditions, since high-pt decays in leptons have the clearest experimental signature. They also allows to estimate with good precision the data luminosity. Finally measurement of the decay lepton spectra from W production gives information on the gluon PDF at low-x and can thus improve knowledge of PDFs.