Longitudinal Double-Spin Asymmetries for Dijet Production at Intermediate Pseudorapidity in Polarized $pp$ Collisions at $\sqrt{s}$ = 200 GeV

TL;DR

This paper reports the first measurements of the longitudinal double-spin asymmetry for dijet production at intermediate pseudorapidity in polarized proton-proton collisions at 200 GeV, providing new data to constrain gluon polarization.

Contribution

It presents the first measurement of $A_{LL}$ for dijets with at least one jet at $0.8<\eta<1.8$ in polarized $pp$ collisions at 200 GeV, extending the kinematic range for gluon polarization studies.

Findings

Measured asymmetries are consistent with global analysis predictions.

Results span parton momentum fractions down to $x \sim 0.01$.

Provides new constraints on gluon polarization in a poorly constrained region.

Abstract

We present the first measurements of the longitudinal double-spin asymmetry $A_{LL}$ for dijets with at least one jet reconstructed within the pseudorapidity range $0.8 < \eta < 1.8$. The dijets were measured in polarized $pp$ collisions at a center-of-mass energy $\sqrt{s}$ = 200 GeV. Values for $A_{LL}$ are determined for several distinct event topologies, defined by the jet pseudorapidities, and span a range of parton momentum fraction $x$ down to $x \sim$ 0.01. The measured asymmetries are found to be consistent with the predictions of global analyses that incorporate the results of previous RHIC measurements. They will provide new constraints on $\Delta g(x)$ in this poorly constrained region when included in future global analyses.