Implications of space-momentum correlations and geometric fluctuations in heavy-ion collisions

TL;DR

This paper explores how initial spatial irregularities and space-momentum correlations in heavy-ion collisions influence the final particle correlations, highlighting the role of collective expansion in translating initial inhomogeneities into observable momentum-space features.

Contribution

It demonstrates through a toy Monte-Carlo model how lumpy initial conditions and collective expansion create specific correlation patterns in heavy-ion collisions.

Findings

Initial density fluctuations translate into momentum correlations.

Collective expansion amplifies initial inhomogeneities.

Correlations differ significantly from proton-proton collisions.

Abstract

The standard picture of heavy-ion collisions includes a collective expansion. If the initial energy density in the collisions is lumpy, then a collective expansion can convert that spatial lumpiness into correlations between final-state particles. Correlations measurements in heavy-ion collisions show several prominent features not present in proton-proton collisions. I argue that many features of these correlations are related to the transference of over-densities from the initial overlap region into momentum-space during the quark gluon plasma phase of the expansion. I show results from a toy Monte-Carlo to illustrate the consequences of lumpy initial conditions and a collective expansion.