Higher moment fluctuations of identified particle distributions from ALICE

TL;DR

This paper presents the first measurements of higher-order cumulants of net-proton distributions in Pb--Pb collisions at LHC energies, providing insights into QCD criticality and freeze-out conditions.

Contribution

It reports novel measurements of up to 4th order cumulants of net-proton distributions at LHC, comparing with RHIC results to aid in understanding QCD phase transition.

Findings

Cumulant ratios vary with collision centrality.

Results are consistent with lattice QCD predictions.

Data can help determine chemical freeze-out parameters.

Abstract

Cumulants of conserved charges fluctuations are regarded as a potential tool to study the criticality in the QCD phase diagram and to determine the freeze-out parameters in a model-independent way. At LHC energies, the measurements of the ratio of the net-baryon (net-proton) cumulants can be used to test the lattice QCD predictions. In this work, we present the first measurements of cumulants of the net-proton number distributions up to $4^{th}$ order in Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 and 5.02 TeV as a function of collision centrality. We compare our cumulant ratios results with the STAR experiment net-proton results measured in the first phase of the Beam Energy Scan program at RHIC. The results can be used to obtain the chemical freeze-out parameters at LHC.