Azimuthal instabilities of the Gribov-Levin-Ryskin equation

TL;DR

This paper proposes that azimuthal instabilities in the generalized GLR equation could explain elliptic flow in nuclear collisions without relying on hydrodynamics, aligning with observed scaling behaviors.

Contribution

It introduces azimuthal dependence into the GLR equation, suggesting a novel QCD-based mechanism for elliptic flow in nuclear collisions.

Findings

GLR equation develops unstable azimuthal modes

Azimuthal dependence in structure functions is plausible

Explains elliptic flow scaling without hydrodynamics

Abstract

We introduce the phenomenology of elliptic flow in nuclear collisions, and argue that its scaling across energies, rapidities and system sizes could be suggestive of a QCD-based rather than a hydrodynamical explanation. As a hypothesis for such an explanation, we show that the GLR equation develops unstable modes when the parton distribution function is generalized to depend on azimuthal angle. This generally means the structure function aquires an azimuthal dependence. We argue that this process is a plausible alternative explanation for the origin of elliptic flow, one that naturally respects the scaling experimentally observed.