Large parity-violating longitudinal single-spin asymmetries ALe +=-0.86-0.14+0.30 and ALe-=0.88-0.71+0.12 are observed for inclusive high transverse momentum electrons and positrons in polarized p+p collisions at a center-of-mass energy of √s=500GeV with the PHENIX detector at RHIC. These e± come mainly from the decay of W± and Z0 bosons, and their asymmetries directly demonstrate parity violation in the couplings of the W± to the light quarks. The observed electron and positron yields were used to estimate W ± boson production cross sections for the e± channels of σ(pp→W+X)×BR(W+→e +νe)=144.1±21.2(stat)-10.3+3.4(syst)±21. 6(norm)pb, and σ(pp→W-X)×BR(W -→e-ν̄e)=31.7±12.1(stat)-8. 2+10.1(syst)±4.8(norm)pb.
|Journal||Physical review letters|
|State||Published - 11 Feb 2011|
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)