Recent results of the STAR high-energy polarized proton-proton program at RHIC at BNL

Abstract

The STAR experiment at the Relativistic Heavy‐Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) is carrying out a spin physics program colliding transverse or longitudinal polarized proton beams at s = 200 – 500GeV to gain a deeper insight into the spin structure and dynamics of the proton. These studies provide fundamental tests of Quantum Chromodynamics (QCD).One of the main objectives of the STAR spin physics program is the determination of the polarized gluon distribution function through a measurement of the longitudinal double‐spin asymmetry, ALL, for various processes. Recent results will be shown on the measurement of ALL for inclusive jet production, neutral pion production and charged pion production at s = 200GeV. In addition to these measurements involving longitudinal polarized proton beams, the STAR collaboration has performed several important measurements employing transverse polarized proton beams. New results on the measurement of the transverse single‐spin asymmetry, AN, for forward neutral pion production and the first measurement of AN for mid‐rapidity di‐jet production will be discussed.