2019/08/05 by Dilks, Christopher
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.1908.01830
The contribution to the spin of the proton from the gluon helicity is starting to come into focus: for gluons carrying a large fraction x of the proton momentum, evidence of positive gluon polarization has been observed, via measurements of the longitudinal double-spin asymmetry ALL for inclusive jet and dijet production. ALL is sensitive to the polarized gluon distribution function, Δg(x), and while it is positive at high x, it is not well constrained for x<0.05. Recent measurements at STAR of observables originating dominantly from quark-gluon and gluon-gluon subprocesses aim to improve the precision of Δg(x) at high x, as well as for the first time provide insight into the low-x contribution. ALL measurements of inclusive jets and dijets at midrapidity (|η|<1) and intermediate rapidity (0.8