The 3D structure of anisotropic flow in small collision systems at the Relativistic Heavy Ion Collider

TL;DR

This paper uses advanced (3+1)D dynamical simulations to study the rapidity dependence of anisotropic flow in small asymmetric nuclear collisions at RHIC, highlighting the role of longitudinal flow decorrelation.

Contribution

It introduces a coupled initial state and hydrodynamics model for small systems and demonstrates the significance of longitudinal flow decorrelation in anisotropic flow measurements.

Findings

Approximately 50% of the $v_3(p_T)$ difference explained by rapidity-dependent reference flow vectors.

Longitudinal flow decorrelation is crucial for understanding anisotropic flow in asymmetric collisions.

Results on beam energy dependence of particle spectra and flow in d+Au collisions.

Abstract

We present (3+1)D dynamical simulations of asymmetric nuclear collisions at the Relativistic Heavy Ion Collider (RHIC). Employing a dynamical initial state model coupled to (3+1)D viscous relativistic hydrodynamics, we explore the rapidity dependence of anisotropic flow in the RHIC small system scan at 200 GeV center of mass energy. We calibrate parameters to describe central $^3$He+Au collisions and make extrapolations to d+Au and p+Au collisions. Our calculations demonstrate that approximately 50% of the $v_3(p_T)$ difference between the measurements by the STAR and PHENIX Collaborations can be explained by the use of reference flow vectors from different rapidity regions. This emphasizes the importance of longitudinal flow decorrelation for anisotropic flow measurements in asymmetric nuclear collisions, and the need for (3+1)D simulations. We also present results for the beam energy dependence of particle spectra and anisotropic flow in d+Au collisions.