Elliptic flow from Coulomb interaction and low density elastic scattering

TL;DR

This paper investigates how Coulomb interactions and elastic scattering in low-density systems can produce elliptic flow anisotropies, offering insights relevant to high-energy heavy ion collision experiments and quantum chromodynamics.

Contribution

It demonstrates that significant elliptic anisotropy can arise from Coulomb and elastic interactions in low-density systems, challenging the exclusive association of flow with hydrodynamics.

Findings

Elliptic anisotropy depends on initial spatial eccentricity.

Both Coulomb interaction and elastic scattering produce anisotropy.

Results provide insights into anisotropic flow in high-energy collisions.

Abstract

In high energy heavy ion collisions and interacting cold atom systems, large elliptic flow anisotropies have been observed. For the large opacity ($\rho\sigma L\sim 10^{3}$) of the latter hydrodynamics is a natural consequence, but for the small opacity ($\rho\sigma L\sim 1$) of the former hydrodynamic description is questionable. To shed light onto the situation, we simulate the expansion of a low density Argon ion (or atom) system, initially trapped in an elliptical region, under the Coulomb interaction (or elastic scattering). Significant elliptic anisotropy is found in both cases, and the anisotropy depends on the initial spatial eccentricity and the density of the system. The results may provide insights into the physics of anisotropic flow in high energy heavy ion collisions and its role in the study of quantum chromodynamics.