Gluon Polarization in Longitudinally Polarized pp Collisions at STAR

Abstract

The STAR Collaboration is performing a wide range of measurements to determine the gluon helicity distribution in the proton. Gluon-gluon and quark-gluon scattering dominate jet production in proton-proton collisions at RHIC, so the longitudinal double-spin asymmetry, [Formula: see text], for jet production places significant constraints on the gluon polarization in the proton. In recent years STAR has recorded large longitudinally polarized [Formula: see text] data sets at both [Formula: see text] GeV and [Formula: see text] GeV. The 2009 STAR inclusive jet [Formula: see text] measurements at [Formula: see text] GeV show the first experimental evidence of non-zero gluon polarization over the Bjorken-[Formula: see text] range, [Formula: see text]. Furthermore, data collected at [Formula: see text] GeV during the 2012 and 2013 RHIC runs allow access to the gluon polarization at lower [Formula: see text]. In this talk, I will present the final results of the 2009 inclusive jet [Formula: see text] measurement at [Formula: see text] GeV, the analysis status of the 2012 inclusive jet [Formula: see text] measurement at [Formula: see text] GeV, and the status of di-jet and other STAR measurements that are sensitive to gluon polarization.