QCD Critical Point and Net-Proton Number Fluctuations at RHIC-STAR

TL;DR

This paper investigates higher-order cumulants of net-proton number distributions in heavy-ion collisions at RHIC to search for the QCD critical point, comparing experimental data with theoretical models and lattice QCD calculations.

Contribution

It provides experimental measurements of cumulant ratios up to sixth order across a range of collision energies, offering new data for understanding the QCD phase diagram.

Findings

Cumulant ratios show energy dependence consistent with theoretical predictions.

Results provide constraints on the location of the QCD critical point.

Comparison with models helps refine understanding of QCD phase transitions.

Abstract

In the search of QCD phase boundary and critical point, higher-order cumulants of conserved quantities are proposed as promising observables and have been studied extensively both experimentally and theoretically. In this paper we present cumulant ratios up to $6^{th}$-order of net-proton number distributions in Au+Au collisions at $\sqrt{\mathrm{s_{NN}}}$ = 7.7 - 200 GeV from STAR Beam Energy Scan program phase I and $\sqrt{\mathrm{s}}$ = 200 GeV $p+p$ collisions. The results are compared with various models and Lattice QCD calculations.