Abstract

We report measurements of the charge-separated W+(-)-> e(+(-))+nu(e)(nu-(e)) and Z/gamma*-> e(+)e(-) production cross sections at mid-rapidity in proton-proton collisions at root s=500 GeV. These results are based on 13.2 pb(-1) of data recorded in 2009 by the STAR detector at RHIC. Production cross sections for W bosons that decay via the e nu channel were measured to be sigma(pp -> W+X)center dot BR(W+-> e(+)nu e)=117.3 +/- 5.9(stat)+/- 6.2(syst)+/- 15.2(lumi) pb, and sigma(pp -> W-X)center dot BR(W--> e(-)(nu)over bar(-)e)=43.3 +/- 4.6(stat)+/- 3.4(syst)+/- 5.6(lumi) pb. For Z/gamma* production, sigma(pp -> Z/gamma*X)center dot BR(Z/gamma*-> e(+)e(-))=7.7 +/- 2.1(stat)-0.9+0.5(syst)+/- 1.0(lumi) pb was measured for di-lepton invariant masses m(e+e-) between 70 and 110 GeV/c(2). First measurements of the W cross section ratio, sigma(pp -> W+X)/sigma(pp -> W-X), at root v=500 GeV are also reported. Theoretical predictions, calculated using recent parton distribution functions, are found to agree with the measured cross sections.