NA61/SHINE results on search for critical point

TL;DR

The NA61/SHINE experiment at CERN searches for the QCD critical point in nucleus-nucleus collisions within 5-17 GeV, analyzing fluctuations and correlations, but has not yet observed definitive signs of it.

Contribution

This paper summarizes the current status of critical point searches, including novel methods for analyzing fluctuations and handling uncertainties in heavy-ion collision data.

Findings

No clear indication of the critical point observed so far.

Development of new methods for analyzing fluctuations and correlations.

Summary of fluctuation and femtoscopy studies in the specified energy range.

Abstract

The NA61/SHINE experiment at the CERN SPS is a multipurpose fixed-target spectrometer for charged and neutral hadron measurements. Its research program includes studies of strong interactions as well as reference measurements for neutrino and cosmic-ray physics. One major goal of its strong interaction program is to determine the existence and pinpoint the location of the QCD critical point, an object of both experimental and theoretical studies. This contribution will summarize the current status of NA61/SHINE critical point searches in nucleus-nucleus collisions, in the collision energy range $\sqrt{s_{NN}} = 5-17$~GeV. The review includes studies of fluctuations of net-electric charge, femtoscopy analysis of $\pi-\pi$ pairs, as well as intermittency of protons and negatively charged hadrons. No clear indication of the critical point has been observed so far. Finally, we report on the development of novel methods aimed at solving the long-standing problem of bin-by-bin correlations in experimental intermittency analysis, and for a more accurate handling of systematics and uncertainties.