Surprises for the Chemical Freeze-out Lines from the New Data in $p$+$p$ and $A$+$A$ Collisions

Abstract

We summarize the surprising results obtained in the fit of the new p+p and updated A+A data on mean multiplicities. The available range of thermal parameters for the NA61/SHINE energy and system-size scan program is squeezed and shifted compared to expectations. The p+p freezeout line touches the A+A line in the vicinity of the K + /π + horn, although the touching point corresponds to different energies in A+A and p+p. It is found that stable fit results for p+p reactions are obtained if particles and antiparticles containing all three conserved charges are measured. It requires at least 6 particles, if strange baryons are not measured, to get the temperature and chemical potential of the freeze-out.