Confronting fluctuations of conserved charges in central nuclear collisions at the LHC with predictions from Lattice QCD

TL;DR

This study compares experimental fluctuations of conserved charges in LHC heavy-ion collisions with Lattice QCD predictions, confirming the thermal nature of the created fireball and its properties near the QCD transition temperature.

Contribution

The paper provides the first experimental extraction of net baryon and strangeness susceptibilities at LHC energies, aligning them with Lattice QCD results and supporting the thermalization hypothesis.

Findings

Fluctuations match Lattice QCD predictions at T_c

Fireball volume exceeds 4000 fm^3 at T_c

Results support thermal origin of the quark-gluon plasma

Abstract

We construct net baryon number and strangeness susceptibilities as well as correlations between electric charge and strangeness from experimental data of the ALICE Collaboration at the CERN LHC. The data were taken in Pb-Pb collisions at $\sqrt{s_{NN}}$=2.76 TeV. The resulting fluctuations and correlations are consistent with Lattice QCD results at the chiral crossover pseudocritical temperature $T_c\simeq 155$ MeV. This agreement lends strong support to the assumption that the fireball created in these collisions is of thermal origin and exhibits characteristic properties expected in QCD at the transition from the quark gluon plasma to the hadronic phase. The volume of the fireball for one unit of rapidity at $T_c$ is found to exceed 4000 fm$^3$. A detailed discussion on uncertainties in the temperature and volume of the fireball is presented. The results are linked to pion interferometry measurements and predictions from percolation theory.