D. R. Oliinychenko, K. A. Bugaev, A. S. Sorin
Here we thoroughly discuss some weak points of the thermal model which is traditionally used to describe the hadron multiplicities measured in the central nucleus-nucleus collisions. In particularly, the role of conservation laws, the values of hard core radii along with the effects of the Lorentz contraction of hadron eigen volumes and the hadronic surface tension are systematically studied. It is shown that for the adequate description of hadron multiplicities the conservation laws should be modified, whereas for the description of hadron yield ratios the conservation laws are not necessary at all. Also here we analyzed the usual criteria for the chemical freeze-out and found that none of them is robust. A new chemical freeze-out criterion of constant entropy per hadron equals to 7.18 is suggested and a novel effect of adiabatic chemical hadron production is discussed. Additionally, we found that the data for the center of mass energies above 10 GeV lead to the temperature of nil surface tension of about T_0 = 147 +- 7 MeV. This is a very intriguing result since a very close estimate for such a temperature was obtained recently within entirely different approach. We argue that these two independently obtained results evidence that the (tri)critical temperature of the QCD phase diagram is between 140 and 154 MeV.
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http://arxiv.org/abs/1204.0103
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