A study of the anisotropy associated with dipole asymmetry in heavy ion collisions

TL;DR

This study investigates the anisotropy linked to initial dipole asymmetry in heavy ion collisions using a multi-phase transport model, revealing how the Fourier coefficient v1 varies with transverse momentum, energy, and other factors.

Contribution

It introduces a method to decompose anisotropy into rapidity-even and momentum conservation components, providing new insights into their dependencies in heavy ion collisions.

Findings

v1 is negative for pT<=0.7-0.9 GeV

v1 peaks at 2-3 GeV and decreases at higher pT

global momentum conservation depends on ta difference for ta<3

Abstract

The anisotropy associated with the initial dipole asymmetry in heavy ion collisions is studied via the two-particle relative azimuthal azimuthal angle (\Delta\phi=\phi^a-\phi^b) correlations, within a multi-phase transport model. For a broad selection of centrality, transverse momenta (pT^{a,b}) and pseudorapidity (\eta^{a,b}), a fitting method is used to decompose the anisotropy into a rapidity-even component, characterized by the Fourier coefficient v1, and a global momentum conservation component. The extracted v1 values are negative for pT<=0.7-0.9 GeV, reach a maximum at 2-3 GeV, and decreases at higher pT. The v1 values vary weakly with \eta and centrality, but increases with collision energy and parton cross-section. The extracted global momentum conservation component is found to depend on \Delta\eta= \eta^a-\eta^b for \Delta\eta<3.