Reconstructing the final state of Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV

TL;DR

This study uses a blast-wave model to analyze transverse-momentum spectra from Pb+Pb collisions at 2.76 TeV, revealing details about freeze-out conditions, resonance behavior, and possible chemical potentials.

Contribution

It introduces a comprehensive blast-wave model fit to multiple particle spectra, providing new insights into freeze-out parameters and resonance decoupling in high-energy heavy-ion collisions.

Findings

Central collisions have freeze-out temperature of 98 MeV.

Transverse expansion velocity averages 0.654 in central collisions.

Hints of chemical potential for charged pions observed.

Abstract

We fit the single-hadron transverse-momentum spectra measured in Pb+Pb collisions at $\sqrt{s_{NN}} = 2.76$ TeV with the blast-wave model that includes production via resonance decays. Common fit to pions, kaons, (anti)protons, and lambdas yields centrality dependence of the freeze-out temperature and transverse expansion velocity. In the most central collisions we see $T=98$ MeV and $\langle v_t \rangle = 0.654$. The $K^*$ resonance fits into this picture but the $\phi$ meson might freeze-out a little earlier. Multistrange baryons seem to decouple at higher temperature and weaker transverse flow. Within our model we observe hints of chemical potential for the charged pions.