Observation of W decay in 500 GeV p+p collisions at RHIC

Abstract

W boson production is observed in $\sqrt{s}=500$ GeV proton proton collisions at RHIC-PHENIX experiment. The single longitudinal spin asymmetry $A_L(\overrightarrow{p}p\rightarrow W^+X)$ is measured via decay positrons in the mid rapidity region. The asymmetry $-0.83\pm0.31\pm(11%$ scale uncertainty) is consistent with calculations from various polarized parton distribution functions.