Search for a critical point of strongly-interacting matter in central $^{40}$Ar +$^{45}$Sc collisions at 13$A$-75$A$ GeV/$c$ beam momentum

TL;DR

This study searches for the critical point of strongly interacting matter in central argon-scandium collisions at various energies using intermittency analysis, but finds no evidence of the expected pattern, setting upper limits on correlations.

Contribution

It introduces an intermittency analysis of proton multiplicity distributions in heavy-ion collisions at CERN SPS energies to search for the critical point.

Findings

No evidence of the critical intermittency pattern was observed.

An upper limit on correlated protons and intermittency index was established.

The results constrain models predicting critical phenomena in such collisions.

Abstract

The critical point of strongly interacting matter is searched for at the CERN SPS by the NA61/SHINE experiment in central $^{40}$Ar +$^{45}$Sc collisions at 13$A$, 19$A$, 30$A$, 40$A$, and 75$A$ GeV/$c$. The dependence of the second-order scaled factorial moments of proton multiplicity distributions on the number of subdivisions in transverse momentum space is measured. The intermittency analysis uses statistically independent data sets for every subdivision in transverse and cumulative-transverse momentum variables. The results obtained do not indicate the searched intermittent pattern. An upper limit on the fraction of correlated protons and the intermittency index is obtained based on a comparison with the Power-law Model.