Precision Measurement of the Longitudinal Double-spin Asymmetry for Inclusive Jet Production in Polarized Proton Collisions at $\sqrt{s}=200$ GeV

TL;DR

This paper presents a high-precision measurement of the longitudinal double-spin asymmetry in inclusive jet production in polarized proton collisions at 200 GeV, providing new insights into gluon polarization.

Contribution

It offers the most precise measurement of $A_{LL}$ at RHIC energies, constraining polarized parton distribution functions and indicating positive gluon polarization for $x>0.05$.

Findings

Evidence for positive gluon polarization in $x>0.05$ region.

Stringent constraints on polarized parton distribution functions.

High-precision $A_{LL}$ measurements at $ oot s=200$ GeV.

Abstract

We report a new high-precision measurement of the mid-rapidity inclusive jet longitudinal double-spin asymmetry, $A_{LL}$, in polarized $pp$ collisions at center-of-mass energy $\sqrt{s}=200$ GeV. The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep inelastic scattering (DIS), semi-inclusive DIS, and RHIC $pp$ data. The measured asymmetries provide evidence for positive gluon polarization in the Bjorken-$x$ region $x>0.05$.