Gluon Polarization Measurements from Correlated Probes

TL;DR

This paper reports preliminary measurements of the dijet longitudinal double spin asymmetry in polarized proton-proton collisions at 200 GeV, providing new insights into the gluon polarization within the proton.

Contribution

It presents the first analysis of the shape of Δg(x) using dijet asymmetry data across multiple pseudorapidity regions at RHIC.

Findings

Constraints on the shape of Δg(x) from pseudorapidity-dependent measurements

Comparison of experimental results with various polarized parton distribution models

First use of dijet asymmetry to probe gluon polarization in this kinematic range

Abstract

These proceedings show the preliminary results of the dijet longitudinal double spin asymmetry $A_{LL}$ in polarized proton-proton collisions at $\sqrt{s} = 200$ GeV for the pseudorapidity range $|\eta| \le 0.8$. The integrated luminosity of 10.6 pb$^{-1}$ used in this analysis was collected during RHIC Run-9. This result is presented as a function of the dijet invariant mass in multiple pseudorapidity acceptances. The division into different pseudorapidity regions allows the kinematics of the hard interaction to be constrained and information about the shape of $\Delta g(x)$ to be extracted for the first time. Comparisons are made with expectations from various different theoretical scenarios of polarized parton distributions of the proton.