The Role of Surface Tension for the Equation of State of Quark-Gluon Bags

The temperature and chemical potential dependent surface tension of bags is introduced into the gas of quark-gluon bags model. The suggested model is solved analytically. It resolves a long standing problem of a unified description of the first and second order phase transition with the cross-over. Such an approach is necessary to model the complicated properties of quark-gluon plasma and hadronic matter from the first principles of statistical mechanics. In addition to the deconfinement phase transition, we found that at the curve of a zero surface tension coefficient there must exist the surface induced phase tranition of the 2-nd or higher order, which separates the pure quark gluon plasma (QGP) from the cross-over states. Thus, the present model predicts that the critical endpoint of quantum chromodynamics is the tricritical endpoint.