Rapidity dependence of azimuthal correlations for p+p and d+Au at $\sqrt{s}=200$GeV

TL;DR

This paper investigates how azimuthal correlations of particles produced in proton-proton and deuteron-gold collisions at 200 GeV vary with rapidity, providing insights into the nuclear gluon density at small Bjorken-x values.

Contribution

It presents new measurements of forward and mid-rapidity azimuthal correlations using STAR's electromagnetic calorimeters, probing the nuclear gluon density at intermediate x.

Findings

Preliminary results on $c0^{0}$-$c0^{0}$ correlations.

Analysis of $c0^{0}$ + jet-like azimuthal correlations.

Sensitivity to nuclear gluon density at small Bjorken-x.

Abstract

Forward di-jet production in d+Au collisions at RHIC provides sensitivity to Bjorken-x between 0.001 and 0.02 for the nuclear gluon density . The STAR experiment at RHIC has continuous azimuthal coverage with electromagnetic calorimeters for pseudo-rapidity from -1 to 4. We have measured forward+mid-rapidity $\pi^{0}-\pi^{0}$ and $\pi^{0}-h$ azimuthal correlations and forward+forward rapidity $\pi^{0}-\pi^{0}$ azimuthal correlations. Both analyses use the Forward Meson Spectrometer (FMS) triggered data in RHIC 2008 run p+p and d+Au collisions at $\sqrt{s_{NN}}$=200 GeV. The end-cap electromagnetic calorimeter (EEMC) at STAR covers pseudo-rapidity from 1.07 to 2. This provides us sensitivity to the nuclear gluon density at intermediate x values. Preliminary results on the $\pi^{0}-\pi^{0}$ and $\pi^{0}$ + jet-like azimuthal correlations with both the FMS and the EEMC will be discussed.