Finding out universal conditions describing the freeze-out parameters was a subject of various phenomenological studies. In the present work, we introduce a new condition based on constant trace anomaly (or interaction measure) calculated in the hadron resonance gas (HRG) model. Various extensions to the {\it ideal} HRG which are conjectured to take into consideration different types of interactions have been analysed. When comparing HRG thermodynamics to that of lattice quantum chromodynamics, we conclude that the hard-core radii are practically irrelevant, especially when HRG includes all resonances with masses less than 2GeV. It is found that the constant trace anomaly (or interaction measure) agrees well with most of previous conditions.
@article{arxiv.1308.1712,
title = {Constant Trace Anomaly as a Universal Condition for the Chemical Freeze-Out},
author = {A. Tawfik},
journal= {arXiv preprint arXiv:1308.1712},
year = {2013}
}