Measurement of double helicity asymmetries ($A_{LL}$) at mid- and forward rapidities in longitudinally polarized $p+p$ collisions at $\sqrt{s}$ = 510 GeV with PHENIX experiment

Abstract

One of the main goals of the RHIC spin program as well as the PHENIX experiment is to determine the gluon spin contribution to the total spin of the nucleon. Recent longitudinally polarized proton-proton collision results at RHIC at a center-of-mass energy of 200 GeV have indicated a nonzero gluon spin contribution at x above 0.05. In recent years RHIC has been operating at a higher center-of-mass energy which allows to extend the covered range. PHENIX has published neutral pion asymmetries at central rapidities which clearly confirm the nonzero gluon contributions and extend the measured range to 0.01. Another measurement of J/ψ asymmetries at forward rapidities extends the sensitivity until 0.001.