Fluctuations in slope parameter in event-by-event hydrodynamics and momentum anisotropy in heavy ion collisions

TL;DR

This study uses event-by-event hydrodynamics to analyze fluctuations in the slope parameter of pion distributions in heavy ion collisions, revealing strong correlations with momentum anisotropy coefficients, which can enhance understanding of collision dynamics.

Contribution

It demonstrates that fluctuations in the slope parameter are strongly correlated with azimuthal anisotropy, providing a new observable for studying final state momentum anisotropy in heavy ion collisions.

Findings

Strong correlation between slope parameter fluctuations and azimuthal distribution coefficients.

Fluctuations in the slope parameter can serve as additional constraints in hydrodynamical models.

Simulations of Au+Au collisions at RHIC energies show measurable azimuthal fluctuations.

Abstract

In event by event hydrodynamic model, we have simulated 30-40\% Au+Au collisions at RHIC and computed the slope parameter from the invariant pion distribution. In each event, the slope parameter fluctuates azimuthally. Fourier expansion coefficients $T_n$ for the slope parameter and the Fourier expansion coefficients $v_n$ for the azimuthal distribution $\frac{dN}{d\phi}$ are found to be strongly correlated. Strong correlation between the two expansion coefficients suggests that in addition to azimuthal distribution, fluctuations in the slope parameter of the invariant distribution can as well be used to study the final state momentum anisotropy in relativistic energy heavy ion collisions. If measured experimentally, they can serve as additional constraint for hydrodynamical modeling.