2009 Baikal Summer School On Physics Of Elementary Particles And Astrophysics
23-30 July 2009
JINR, Dubna, and Irkutsk State University, Irkutsk
[en] The two-Higgs-doublet model (2HDM) realizes ground states (vacuum) with different properties for different parameter values. The parameters of the effective potential change during cooling of the Universe after the Big Bang. In so doing, the properties of vacuum state can be affected, phase transitions take place. The evolution of phase states and the set of phase transitions can turn out to be much wider than those accounted for within the conventional Standard model (SM) with a single Higgs doublet. The phase history of the Universe is analyzed for any specified set of the 2HDM parameters. All possible variants of the history are considered. Sets of modern, observed, in principle, parameters corresponding to different sequences of thermal phase transitions are determined. Possible cosmological consequences are briefly discussed.