Multiplicity fluctuations of net protons on the hydrodynamic freeze-out surface

TL;DR

This paper investigates net proton fluctuations at the QCD critical point using hydrodynamic models, comparing baseline calculations with experimental cumulant data, and highlights the over-prediction issues related to static critical fluctuations.

Contribution

It provides a detailed analysis of net proton fluctuation cumulants near the QCD critical point using hydrodynamic freeze-out models, incorporating baseline comparisons.

Findings

Reproduces energy-dependent $C_4$ and $ ext{kappa} \sigma^2$ of net protons

Over-predicts $C_2$ and $C_3$ due to static critical fluctuations

Baseline models approximate experimental cumulant trends

Abstract

This proceeding briefly summarizes our recent work on calculating the correlated fluctuations of net protons on the hydrodynamic freeze-out surface near the QCD critical point. For both Poisson and Binomial baselines, our calculations could roughly reproduce the energy dependent cumulant $C_4$ and $\kappa \sigma^2$ of net protons, but always over-predict $C_2$ and $C_3$ due to the positive contributions from the static critical fluctuations.