Quark-gluon bags with surface tension

Abstract

The temperature and chemical potential dependent surface tension of bags is introduced into the gas of a quark-gluon bags model. This resolves a long standing problem of a unified description of the first- and second-order phase transition with the crossover. Such an approach is necessary to model the complicated properties of quark-gluon plasma and hadronic matter from the first principles of statistical mechanics. The suggested model has an exact analytical solution and allows one to rigorously study the vicinity of the critical endpoint of the deconfinement phase transition. The existence of higher order phase transitions at the critical endpoint is discussed. In addition, we found that at the curve of a zero surface tension coefficient there must exist the surface induced phase transition of the second or higher order, which separates the pure quark-gluon plasma (QGP) from the crossover states, which are the mixed states of hadrons and QGP bags. Thus, the present model predicts that the critical endpoint of quantum chromodynamics is the tricritical endpoint.