Longitudinal double-spin asymmetry for inclusive jet and dijet production in polarized proton collisions at $\sqrt{s}=200$ GeV

TL;DR

This paper presents high-precision measurements of the double-spin asymmetry in polarized proton collisions, providing new insights into the gluon helicity distribution and confirming its positivity for certain momentum fractions.

Contribution

It offers novel, more precise measurements of $A_{LL}$ for inclusive jet and dijet production, enhancing understanding of gluon polarization in protons.

Findings

Results agree with previous measurements and theoretical models.

Data indicates $ riangle g(x,Q^2)$ is positive for $x > 0.05$.

Improved precision strengthens evidence for gluon polarization.

Abstract

We report high-precision measurements of the longitudinal double-spin asymmetry, $A_{LL}$, for midrapidity inclusive jet and dijet production in polarized $pp$ collisions at a center-of-mass energy of $\sqrt{s}=200\,\mathrm{GeV}$. The new inclusive jet data are sensitive to the gluon helicity distribution, $\Delta g(x,Q^2)$, for gluon momentum fractions in the range from $x \simeq 0.05$ to $x \simeq 0.5$, while the new dijet data provide further constraints on the $x$ dependence of $\Delta g(x,Q^2)$. The results are in good agreement with previous measurements at $\sqrt{s}=200\,\mathrm{GeV}$ and with recent theoretical evaluations of prior world data. Our new results have better precision and thus strengthen the evidence that $\Delta g(x,Q^2)$ is positive for $x > 0.05$.