Measurement of the Transverse Single-Spin Asymmetry in p ↑ + p → W ± / Z 0 at RHIC
Physical Review Letters
We present the measurement of the transverse single-spin asymmetry of weak boson production in transversely polarized proton-proton collisions at s=500 GeV by the STAR experiment at RHIC. The measured observable is sensitive to the Sivers function, one of the transverse-momentum-dependent parton distribution functions, which is predicted to have the opposite sign in proton-proton collisions from that observed in deep inelastic lepton-proton scattering. These data provide the first experimental investigation of the nonuniversality of the Sivers function, fundamental to our understanding of QCD.
Adamczyk, L., Adkins, J. K., et. al. (2016). Measurement of the transverse single-spin asymmetry in p ↑+p →w± /Z0 at RHIC. Physical Review Letters, 116(13), . DOI: 10.1103/PhysRevLett.116.132301