Chemical freeze-out of strange particles and possible root of strangeness suppression

¹ Bogolyubov Institute for Theoretical Physics - Metrologichna str. 14 B, Kiev 03680, Ukraine
² Department of Physics, University of Cape Town - Ronebosch 7701, South Africa
³ FIAS, Goethe-University - Ruth-Moufang Str. 1, 60438 Frankfurt upon Main, Germany
⁴ Kurchatov Institute, Russian Research Center - Kurchatov Sqr., Moscow, 123182, Russia
⁵ Laboratory for Information Technologies, JINR - Joliot-Curie str. 6, 141980 Dubna, Russia

^(a) bugaev@th.physik.uni-frankfurt.de

Received: 24 August 2013
Accepted: 22 October 2013

Abstract

Two approaches to treat the chemical freeze-out of strange particles in the hadron resonance gas model are analyzed. The first one employs their non-equillibration via the usual factor and such a model describes the hadron multiplicities measured in nucleus-nucleus collisions at AGS, SPS and RHIC energies with . 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. This approach is based on the conservation laws which allow us to connect the freeze-outs of strange and non-strange hadrons. Within the suggested approach the same set of hadron multiplicities can be described better than within the conventional approach with .