Longitudinal Double Spin Asymmetry in Inclusive Jet Production at STAR

TL;DR

This paper presents the first measurement of the longitudinal double-spin asymmetry in inclusive jet production in polarized proton-proton collisions at RHIC, providing insights into gluon polarization within the proton.

Contribution

It reports the first measurement of $A_{LL}$ for inclusive jets at $ oot{0.4} ext{GeV}$, constraining models of gluon polarization in the proton.

Findings

Results agree with perturbative QCD predictions.

Disfavor large positive gluon polarization.

Provides new constraints on gluon polarization models.

Abstract

This contribution reports on the first measurement of the longitudinal double-spin asymmetry $A_{LL}$ for the inclusive production of jets in polarized proton-proton collisions at $\sqrt{s}=200 \mathrm{GeV}$. The data were collected with STAR at RHIC in the years 2003 and 2004, and correspond to a sampled integrated luminosity of $0.3 \mathrm{pb}^{-1}$ with beam polarizations up to 45%. The results on $A_{LL}$ cover jet transverse momenta $5 < p_{T} < 17 \mathrm{GeV/c}$ and agree with perturbative QCD evaluations based on deep-inelastic scattering parametrizations for the gluon polarization in the proton. The results disfavor large positive gluon polarization in the polarized proton.