Multiparticle correlations and collectivity in small systems from the initial state

TL;DR

This paper explores initial state models to explain multiparticle correlations in small collision systems, challenging the hydrodynamic interpretation and demonstrating the potential of the Color Glass Condensate framework.

Contribution

It introduces an initial state approach to multiparticle correlations, providing an alternative to hydrodynamics in small systems, and compares models with experimental data.

Findings

Initial state models qualitatively reproduce observed correlations.

Color Glass Condensate framework offers a viable alternative explanation.

Model improvements can enhance agreement with experimental results.

Abstract

We report on recent progress in understanding multiparticle correlations in small systems from the initial state. First, we consider a proof-of-principle parton model, which we use to demonstrate that many of the multiparticle correlations observed in light-heavy ion collisions, often ascribed to hydrodynamic collectivity, can be qualitatively reproduced in an initial state model. Then, we study the two-particle harmonics $v_2$ and $v_3$ for p/d/$^3$He+Au collisions at RHIC using the dilute-dense Color Glass Condensate Effective Field Theory framework. We show that this provides a viable alternative explanation to hydrodynamics, and elaborate on how such modeling can be improved.