Azimuthal Anisotropy Relative to the Participant Plane from AMPT in Central p+Au, d+Au, and $^{3}$He+Au Collisions at $\sqrt{s_{NN}}=200$ GeV

TL;DR

This study uses the AMPT model with a detailed wave function of helium-3 to analyze azimuthal anisotropy in small collision systems at RHIC, comparing results with experimental data and exploring the evolution of anisotropy.

Contribution

It extends previous AMPT studies by incorporating a full wave function of helium-3 and analyzing anisotropy moments in p+Au, d+Au, and $^3$He+Au collisions at RHIC.

Findings

Reasonable agreement with $v_2$ in d+Au and $^3$He+Au for $p_T \, extless \, 1$ GeV/c.

Underestimation of $v_2$ and $v_3$ at higher $p_T$ values.

Predicted anisotropy patterns based on the number of hot spots from intrinsic geometry.

Abstract

Recent data from p+p and p+Pb collisions at the Large Hadron Collider (LHC), and d+Au and $^3$He+Au collisions at the Relativistic Heavy Ion Collider (RHIC) reveal patterns that---when observed in the collision of heavy nuclei---are commonly interpreted as indicators of a locally equilibrated system in collective motion. The comparison of these data sets, including the forthcoming results from p+Au and p+Al collisions at RHIC, will help to elucidate the geometric dependence of such patterns. It has recently been shown that A-Multi-Phase-Transport-Model (AMPT) can describe some of these features in LHC data with a parton-parton scattering cross section comparable to that required to describe A+A data. In this paper, we extend these studies by incorporating a full wave function description of the $^3$He nucleus to calculate elliptical and triangular anisotropy moments $v_2$ and $v_3$ for p+Au, d+Au and $^3$He+Au collisions at the RHIC top energy of 200 GeV. We find reasonable agreement with the measured $v_2$ in d+Au and $^3$He+Au and $v_3$ in $^3$He+Au for transverse momentum ($p_{T}$) $\lesssim$ 1 GeV/c, but underestimate these measurements for higher values of \pt. We predict a pattern of coefficients ($v_{2}$, $v_{3}$) for \pau, dominated by differences in the number of induced local hot spots (i.e. one, two, or three) arising from intrinsic geometry. Additionally, we examine how this substantial azimuthal anisotropy accrues during each individual evolutionary phase of the collision in the AMPT model. The possibility of a simultaneous description of RHIC- and LHC-energy data, the suite of different geometries, and high multiplicity p+p data is an exciting possibility for understanding the underlying physics in these systems.