Measurement of the W→eν and Z/γ *→e +e - production cross sections at mid-rapidity in proton-proton collisions at √s=500GeV

Abstract

We report measurements of the charge-separated W +( -)→e +( -) +ν e(ν ̄e) and Z/γ *→e +e - production cross sections at mid-rapidity in proton-proton collisions at √s=500GeV. These results are based on 13.2pb -1 of data recorded in 2009 by the STAR detector at RHIC. Production cross sections for W bosons that decay via the eν channel were measured to be σ(pp→W +X)•BR(W +→e +ν e)=117.3±5.9(stat)±6.2(syst)±15.2(lumi)pb, and σ(pp→W -X)•BR(W -→e -ν ̄e)=43.3±4.6(stat)±3.4(syst) ±5.6(lumi)pb. For Z/γ * production, σ(pp→Z/γ *X)•BR(Z/γ *→e +e -)=7.7±2.1(stat)-0.9+0. 5(syst)±1.0(lumi)pb was measured for di-lepton invariant masses me +e - between 70 and 110GeV/c2. First measurements of the W cross section ratio, σ(pp→W +X)/σ(pp→W -X), at √s=500GeV are also reported. Theoretical predictions, calculated using recent parton distribution functions, are found to agree with the measured cross sections. © 2012 American Physical Society.