RECENT STAR RESULTS ON W PRODUCTION AND ASYMMETRY IN POLARIZED (p~→) + (p~→) COLLISIONS AT s~1/2 = 500 GeV

摘要

The production of W~± bosons in longitudinally polarized proton-proton collisions at RHIC is a unique way to study the flavor-dependent spin structure of the proton, since at leading order it couples directly and exclusively to specific quark flavor pairings: u + d → W~+ and u + d → W~-. Measurement of the longitudinal single-spin asymmetry of the electron decay daughters in W production is sensitive to the polarizations of the quarks involved. Results from the first proton-proton collisions at s~1/2 = 500 GeV in 2009 are presented, along with a discussion of the forward-rapidity tracking upgrade.