Condition driving chemical freeze-out

We propose that it is the entropy density which characterizes the chemical freeze-out of hadrons in heavy-ion collision experiments. Taking its value from lattice QCD calculations at zero chemical potential, we find that it is excellent in reproducing all experimentally estimated statistical freeze-out parameters, temperature and baryon-chemical potential. We conclude that s/T3 characterizes very well the final states observed in all heavy-ion experiments. (author)