TRANSVERSE SINGLE-SPIN ASYMMETRY MEASUREMENTS AT STAR

摘要

Transverse single-spin asymmetries A_N are expected to be sensitive to parton polarization and orbital angular momentum contributions to the nucleon spin. Significantly large A_N has been observed in different collision systems such as semi-inclusive deep inelastic scattering (SIDIS) and polarized proton-proton (pp) collisions, indicating a dominant contribution of partonic interactions in the nonperturbative regime. Therefore it is critical to measure A_N in various channels of polarized pp collisions in order to complement SIDIS data and to constrain theoretical models. We report STAR asymmetry measurements on midrapidity hadron-jet and dihadron correlations at s~1/2 = 200 GeV and forward rapidity inclusive hadron production at s~1/2 = 500 GeV polarized pp collisions.