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Non-smooth Chemical Freeze-out and Apparent Width of Wide Resonances and Quark Gluon Bags in a Thermal Environment

Here we develop the hadron resonance gas model with the Gaussian width of hadron resonances. This model allows us to treat the usual hadrons and the quark gluon bags on the same footing and to study the stability of the results obtained within different formulations of the hadron resonance gas model. In this work we perform a successful fit of 111 independent hadronic multiplicity ratios measured for $\sqrt{s_{NN}} $= 2.7- 200 GeV. We demonstrate that in a narrow range of collision energy $\sqrt{s_{NN}} =$ 4.3-4.9 GeV there exist peculiar irregularities in various thermodynamic quantities found at chemical freeze-out. The most remarkable irregularity is an unprecedented jump of the number of effective degrees of freedom observed in this narrow energy range which is seen in all realistic versions of the hadron resonance gas model. Therefore, the developed concept is called the non-smooth chemical freeze-out. We are arguing that these irregularities evidence for the possible formation of quark gluon bags. In order to develop other possible signals of their formation here we study the apparent width of wide hadronic resonances and quark gluon bags in a thermal environment. Two new effects generated for the wide resonances and quark gluon bags by a thermal medium are discussed here: the near threshold thermal resonance enhancement and the near threshold thermal resonance sharpening. On the basis of the new effects we argue that the most optimistic chance to find experimentally the quark gluon bags may be related to their sharpening and enhancement in a thermal medium. In this case the wide quark gluon bags may appear directly or in decays as narrow resonances that are absent in the tables of elementary particles and that have the apparent width about 50-120 MeV and the mass about or above 2.5 GeV.