Chemical Freeze-out of Strange Particles and Possible Root of Strangeness Suppression

Understand

Two approaches to treat the chemical freeze-out of strange particles in hadron resonance gas model are analyzed.

• The first one employs their non-equillibration via the usual \gamma_s factor and such a model describes the hadron multiplicities measured in nucleus-nucleus collisions at AGS, SPS and RHIC energies with \chi^2/dof = 1.15.
• Surprisingly, at low energies we find not the strangeness suppression, but its enhancement.
• Also we suggest an alternative approach to treat the strange particle freeze-out separately, but with the full chemical equilibration.