Single-freeze-out model for ultra relativistic heavy-ion collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV and the LHC proton puzzle

TL;DR

This paper applies a single-freeze-out model to analyze hadron spectra in Pb+Pb collisions at 2.76 TeV at the LHC, achieving good agreement except for protons and antiprotons, and uses HBT radii to refine freeze-out hypersurface assumptions.

Contribution

The study introduces a refined single-freeze-out model with optimized hypersurface parameters to better describe hadron spectra and HBT radii in ultra-relativistic heavy-ion collisions.

Findings

Good agreement with data for most hadrons except protons/antiprotons

Discrepancy ratio for proton spectra decreases with increasing p_T

HBT radii analysis constrains freeze-out hypersurface shape

Abstract

The single-freeze-out model with parametrized hypersurface and flow geometry is employed to analyze the transverse-momentum spectra of hadrons produced in the Pb+Pb collisions at the collision energy of {$\sqrt{s_{\rm NN}}=2.76$ TeV} at the CERN Large Hadron Collider (LHC). With the notable exception for protons and antiprotons, we find a very good agreement between the model results and the data for the measured hadron species. The additional analysis of the HBT radii of pions helps us to select, from several different types of freeze-out studied in this work, the most realistic form of the freeze-out hypersurface. We find that discrepancy ratio between the model and experiment for the proton/antiproton spectra depends on $p_T$, dropping from 2 in the soft region to 1 around $p_T=1.5$ GeV.