title: Testing the time-reversal modified universality of the Sivers function.
abstract: We derive the time-reversal modified universality for both quark and gluon Sivers functions from the parity and time-reversal invariance of QCD. We calculate the single transverse-spin asymmetry of inclusive lepton from the decay of W bosons in polarized proton-proton collision at the Brookhaven National Laboratory Relativistic Heavy Ion Collider (RHIC), in terms of the Sivers function. We find that, although the asymmetry is diluted from the W decay, the lepton asymmetry is at the level of several percent and is measurable for a good range of lepton rapidity at RHIC. We argue that this measurable lepton asymmetry at RHIC is an excellent observable for testing the time-reversal modified universality of the Sivers function.
authors.affiliation: Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA. kangzb@iastate.edu
authors.forename: Zhong-Bo
authors.initials: ZB
authors.lastname: Kang
authors.forename: Jian-Wei
authors.initials: JW
authors.lastname: Qiu