Symmetry breaking in two-Higgs-doublet standard model

Different variants of symmetry breaking in the two-Higgs-doublet standard model are analysed with the help of a general method which exploits the symmetrical properties of the system only. It is shown that the total number of phases in the model under consideration is equal to six. Among them there are: one highly symmetric phase, two one-condensate phases, one normal two-condensate phases and two phases with broken electromagnetic symmetry. The symmetries of the phases and the possibilities of second-order phase transitions between the phases are investigated. Within the framework of the four-power non-equilibrium free energy functional, the stability of all phases is investigated and the corresponding phase diagram is constructed. The results are shown to be in agreement with those obtained by the general method. (author)