First Results from ATLAS on W and Z Boson Production in proton-proton Collisions at $\sqrt{s}$=7,$TeV

First measurements by the ATLAS experiment are presented of the W and Z production cross section. The observed 118 W and 125 Z candidates were produced in pp collisions at sqrt{s}=7 TeV at the LHC. The total integrated luminosities correspond to approximately 17/nb for the W and 225/nb for the Z. The total inclusive W-boson production cross section times the leptonic branching ratio is measured to be [8.5 pm 1.3(stat) pm 0.7 (syst) pm 0.9 (lumi)] nb for the W to enu channel and [10.3 pm 1.3(stat) pm 0.8 (syst) pm 1.1(lumi)] nb for the W to munu channel. The total inclusive Z-boson production cross section times leptonic branching ratio within the invariant mass window 66<mll<116 GeV was measured to be [0.72 pm 0.11(stat) pm 0.10(syst) pm 0.08(lumi)]nb for the Z to ee channel and [0.89 pm 0.10(stat) pm 0.07(syst) pm 0.10(lumi)] nb for the Z to mumu channel. Both cross section values are in good agreement with theoretical calculations at NNLO in QCD. In addition the expected charge asymmetry between the cross sections for W+ and W- production is experimentally confirmed.