New results on fluctuations and correlations from the NA61/SHINE experiment at the CERN SPS

TL;DR

This paper reports on NA61/SHINE experiment results exploring fluctuations and correlations in various collision systems to locate the QCD critical point, providing new data on momentum and charge fluctuations across different energies and system sizes.

Contribution

It presents new measurements of fluctuations and correlations in p+p, Be+Be, and Ar+Sc collisions, advancing the search for the QCD critical point.

Findings

Results on transverse momentum fluctuations

Results on multiplicity fluctuations

Higher order moments of net-charge fluctuations

Abstract

The exploration of the QCD phase diagram is the most important task of present heavy ion experiments. In particular, we want to study the phase transition from hadronic to partonic matter and look for the critical point (CP) of strongly interacting matter. Fluctuations and correlations in kinematic characteristics and particle yields may help to locate the CP (in analogy to enlarged fluctuations due to critical opalescence close to a CP in a liquid/gas transition). The strong interactions program of the NA61/SHINE experiment may allow to discover or rule out the existence of the CP in the Super Proton Synchrotron energy domain. For this purpose we perform a two-dimensional scan by varying the energy ($5.1 < \sqrt{s_{NN}} < 16.8/17.3$ GeV) and the system size (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb) of the collisions. In this report new NA61/SHINE results on fluctuations and correlations in p+p, Be+Be, and Ar+Sc collisions are presented. In particular, results on transverse momentum and multiplicity fluctuations, as well as higher order moments of net-charge fluctuations are discussed. The NA61/SHINE data are compared to predictions of string hadronic models and to NA49 results.