Thermal model for Pb+Pb collisions at $\sqrt{s}_{NN} = 2.76$ TeV with explicit treatment of hadronic ground states

TL;DR

This paper extends the thermal model for Pb+Pb collisions at 2.76 TeV to explicitly include hadronic ground state condensation, providing better agreement with observed particle ratios and spectra.

Contribution

It introduces a modified thermal model that explicitly incorporates pion Bose condensation, linking equilibrium and non-equilibrium approaches.

Findings

Good fit to hadron multiplicities and spectra

Indication of pion Bose condensation in central collisions

Proposes a generalized thermal framework

Abstract

Various explanations of the anomalous proton to pion ratio at the LHC are discussed. The special emphasis is set on the Cracow thermal model with single freeze-out. This model allows to get a good agreement for both the mean hadron multiplicities and the spectra. Moreover, the values of the fit parameters indicate the possibility of pion Bose condensation in the most central collisions at the LHC. Therefore, a modification of the thermal framework is proposed that explicitly allows for the condensation in the ground state. The generalised model makes a link between equilibrium and non-equilibrium thermal models. It also suggests that the pion condensation may be formed in the central collisions.