Correlation between initial spatial anisotropy and final momentum anisotropies in relativistic heavy ion collisions

TL;DR

This study investigates how the initial spatial anisotropy in relativistic heavy ion collisions influences the final momentum anisotropy, revealing dependencies on collision centrality, particle type, and transverse momentum through hydrodynamical modeling.

Contribution

It provides a detailed analysis of the correlation between initial geometry and final momentum anisotropy, including dependencies on particle mass, transverse momentum, and shear viscosity.

Findings

Stronger correlation in central collisions and for n=2.

Mass and p_T dependence of correlation strength.

Fluctuations in flow depend on shear viscosity, especially at low p_T.

Abstract

The particle momentum anisotropy ($v_n$) produced in relativistic nuclear collisions is considered to be a response of the initial geometry or the spatial anisotropy $\epsilon_n$ of the system formed in these collisions. The linear correlation between $\epsilon_n$ and $v_n$ quantifies the efficiency at which the initial spatial eccentricity is converted to final momentum anisotropy in heavy ion collisions. We study the transverse momentum, collision centrality, and beam energy dependence of this correlation for different charged particles using a hydrodynamical model framework. The ($\epsilon_n -v_n$) correlation is found to be stronger for central collisions and also for n=2 compared to that for n=3 as expected. However, the transverse momentum ($p_T$) dependent correlation coefficient shows interesting features which strongly depends on the mass as well as $p_T$ of the emitted particle. The correlation strength is found to be larger for lighter particles in the lower $p_T$ region. We see that the relative fluctuation in anisotropic flow depends strongly in the value of $\eta/s$ specially in the region $p_T <1$ GeV unlike the correlation coefficient which does not show significant dependence on $\eta/s$.