Azimuthal distributions of radial momentum and velocity in relativistic heavy ion collisions

TL;DR

This paper introduces azimuthal distributions of radial momentum and velocity in relativistic heavy ion collisions, using the AMPT model to analyze their sensitivity to anisotropic expansion and thermal motion effects.

Contribution

It proposes new azimuthal distribution measures for radial momentum and velocity, providing insights into anisotropic expansion in heavy ion collisions.

Findings

Total radial momentum distribution is highly sensitive to anisotropic expansion.

Mean radial velocity includes contributions from thermal motion and flow.

Distributions help distinguish effects of expansion and thermal motion.

Abstract

Azimuthal distributions of radial (transverse) momentum, mean radial momentum, and mean radial velocity of final state particles are suggested for relativistic heavy ion collisions. Using transport model AMPT with string melting, these distributions for Au + Au collisions at 200 GeV are presented and studied. It is demonstrated that the distribution of total radial momentum is more sensitive to the anisotropic expansion, as the anisotropies of final state particles and their associated transverse momentums are both counted in the measure. The mean radial velocity distribution is compared with the radial {\deg}ow velocity. The thermal motion contributes an isotropic constant to mean radial velocity.