Probing proton spin structure via heavy flavor production in PHENIX

Abstract

The measurement of spin asymmetries in polarized p+p collisions provides an opportunity to probe the spin structure of nucleons. With transversely and longitudinally polarized proton beams at RHIC, we can measure both double longitudinal spin asymmetry ALL and single transverse spin asymmetry AN. At the RHIC energy, heavy quark (charm and beauty) production is dominated by gluon–gluon interactions, so measurements of ALL and AN will allow us to directly probe the polarized gluon distribution and gluon's Sivers functions, respectively. PHENIX experiment collected 3.5 pb−1 (beam polarization ∼50%) and 10 pb−1 (beam polarization ∼60%) data from year 2005 and 2006 runs, respectively. In this analysis, the J/Ψ have been measured through the J/Ψ → μ+μ− channel at forward rapidities, and about 30 000 J/Ψ candidates are reconstructed from Lvl2 triggered data production. We present the latest results of J/ΨALL and AN measurements at forward rapidities from the PHENIX experiment.