Ripples of the QCD Critical Point

TL;DR

This paper studies how the QCD critical point influences baryon number fluctuations in heavy-ion collisions, using advanced theoretical models constrained by first principles, and predicts observable signatures to guide future experiments.

Contribution

It introduces a QCD-assisted effective theory incorporating the CEP and baryon conservation, providing detailed predictions of fluctuation signals near the critical point.

Findings

A prominent peak in baryon number fluctuations linked to the CEP.

The fluctuation peak's amplitude depends on the CEP's location.

The peak position is sensitive to the freeze-out conditions.

Abstract

We investigate the impact of a critical end point (CEP) on the experimentally accessible baryon number fluctuations of different orders. By now, its potential location has been constrained fairly accurately within first principles functional QCD, together with the location of the chiral crossover line and further thermodynamic observables. This information is incorporated in an advanced QCD-assisted low energy effective theory which is used for the computation of baryon number fluctuations at the chemical freeze-out. This computation also takes care of global baryon number conservation at larger density, where the system changes from grand-canonical to canonical statistics. We observe a prominent peak structure, whose amplitude depends on the location of the CEP, while its position is more sensitive to the location of the freeze-out curve. Our results provide guidance for future low energy heavy-ion experiments.