Origin of the localized Pb–Pb and Au–Au correlation difference

Determine whether the localized difference between Pb–Pb and Au–Au collisions in the correlation between the squared elliptic-flow proxy and mean transverse momentum reflects genuine physics or a limitation of the current neural networks.

Background

The paper estimates the correlation between elliptic flow and mean transverse momentum using the initial eccentricity as a proxy for elliptic flow. This correlation is largely insensitive to whether centrality is defined from the final-state charged-particle multiplicity or the initial entropy and is similar in Pb–Pb and Au–Au collisions over most of the centrality range.

A marked discrepancy appears between 10% and 20% centrality, where the Pb–Pb correlation is stronger than the Au–Au correlation. The authors do not determine whether this localized difference arises from physical collision-system effects or from limitations of the neural-network emulators.