Anisotropic flows from initial state of a fast nucleus

TL;DR

This paper investigates azimuthal anisotropy in heavy ion collisions, revealing that initial state effects can produce nonzero anisotropy even without final state interactions, highlighting the role of partonic structure.

Contribution

It introduces a reggeon approach to analyze initial state azimuthal anisotropy, emphasizing effects independent of final state interactions.

Findings

Azimuthal anisotropy exists without final state interactions.

Partonic structure influences initial state anisotropy.

Feynman diagram analysis clarifies the mechanism.

Abstract

We analyze azimuthal anisotropy in heavy ion collisions related to the reaction plane in terms of standard reggeon approach and find that it is nonzero even when the final state interaction is switched off. This effect can be interpreted in terms of partonic structure of colliding nuclei. We use Feynman diagram analysis to describe details of this mechanism. Main qualitative features of the appropriate azimuthal correlations are discussed.