Speed of sound and baryon cumulants in heavy-ion collisions

TL;DR

This paper proposes a method to estimate the speed of sound and its derivative in matter created in heavy-ion collisions using baryon number cumulants, aiding the exploration of the QCD phase diagram.

Contribution

It introduces a novel approach linking baryon cumulants to the speed of sound, providing a new tool for analyzing the phase diagram of strongly interacting matter.

Findings

Method successfully estimates speed of sound in models

Cumulants reveal behavior of sound speed in phase diagram

Application to experimental data suggests potential insights

Abstract

We present a method that may allow an estimate of the value of the speed of sound as well as its logarithmic derivative with respect to the baryon number density in matter created in heavy-ion collisions. To this end, we utilize well-known observables: cumulants of the baryon number distribution. In analyses aimed at uncovering the phase diagram of strongly interacting matter, cumulants gather considerable attention as their qualitative behaviour along the explored range of collision energies is expected to aid in detecting the QCD critical point. We show that the cumulants may also reveal the behavior of the speed of sound in the temperature and baryon chemical potential plane. We demonstrate the applicability of such estimates within two models of nuclear matter, and explore what might be understood from known experimental data.