Updates to the p+p and A+A chemical freeze-out lines from the new experimental data

TL;DR

This paper updates the chemical freeze-out lines for p+p and A+A collisions using new experimental data and resonance information, revealing closer temperatures and new puzzles in collision dynamics.

Contribution

It provides revised freeze-out lines based on recent data, showing smaller temperatures at high energies and closer p+p and A+A lines, highlighting new challenges in understanding collision systems.

Findings

A+A freeze-out line shows smaller temperatures at high energies.

p+p and A+A lines are closer than previously thought.

Chemical potentials may differ significantly at the same energies.

Abstract

We show that the new data on mean multiplicities measured in p+p and A+A collisions together with the updated list of resonances lead to the significant changes of the obtained freeze-out lines. The new A+A line gives much smaller temperatures at high collision energies and agrees with the values obtained at the LHC. The newly obtained p+p line is much closer to the A+A line than previously expected, and even touches it in the region where the $K^+/\pi^+$ horn appears in the data. It indicates that the temperatures that will be obtained in the beam energy and system size scan by the NA61/SHINE Collaboration might be very close. However, our analysis shows that the chemical potentials could be very different for the same energies in A+A and p+p. It adds more puzzles to the set of surprising coincidences at the energies close to the possible onset of deconfinement.