Probing High Parton Densities at Low-$x$ in d+Au Collisions at PHENIX Using the New Forward and Backward Muon Piston Calorimeters

TL;DR

This paper reports on measurements of low-$x$ parton densities in d+Au collisions at PHENIX using new calorimeters, aiming to observe gluon saturation effects through azimuthal correlation analysis.

Contribution

It introduces the use of new forward and backward Muon Piston Calorimeters to measure azimuthal correlations, providing novel insights into gluon saturation at low-$x$ in d+Au collisions.

Findings

Observed differences in correlation widths between d+Au and p+p collisions.

Computed the nuclear modification factor $I_{dA}$ for forward $C0^0$ production.

Provided evidence supporting gluon saturation phenomena.

Abstract

The new forward Muon Piston Calorimeters allow PHENIX to explore low-$x$ parton distributions in d+Au collisions with hopes of observing gluon saturation. We present a two-particle azimuthal $\Delta \phi$ correlation measurement made between a mid-rapidity particle ($|\eta_1| < 0.35$) and a forward $\pi^0$ ($3.1 < \eta_2 < 3.9$) wherein we compare correlation widths in d+Au to p+p and compute $I_{dA}$.