Determination of polarized parton distribution functions with recent data on polarization asymmetries

Global analysis has been performed within the next-to-leading order in quantum chromodynamics (QCD) to determine polarized parton distributions with new experimental data in spin asymmetries. The new data set includes J-Lab, HERMES, and COMPASS measurements on spin asymmetry A₁ for the neutron and deuteron in lepton scattering. Our new analysis also utilizes the double-spin asymmetry for π⁰ production in polarized pp collisions, A_LL^π0, measured by the PHENIX Collaboration. Because of these new data, uncertainties of the polarized PDFs are reduced. In particular, the J-Lab, HERMES, and COMPASS measurements are valuable for determining Δd_v(x) at large x and Δq¯(x) at x∼0.1. The PHENIX π⁰ data significantly reduce the uncertainty of Δg(x). Furthermore, we discuss a possible constraint on Δg(x) at large x by using the HERMES data on g₁^d in comparison with the COMPASS ones at x∼0.05.