Electroweak gauge theory vacuum in a strong magnetic field in a thermostat

Expressions are obtained for the thermodynamical potential of an electrically charged vector boson gas in a magnetic field and for the effective potential of the Weinberg-Salam theory in a strong magnetic field in the thermostat. The estimation of the critical temperature Tcr which corresponds to the phase transition in the Weinberg-Salam theory is given in the one-loop approximation. It is shown how to define property the total probability of the W+W- pair production from the vacuum by a superstrong magnetic field. Its expression is found. Arguments are presented in favour of the fact that in the Weinberg-Salam theory the restoration of a spontaneously-broken symmetry at T=0, B>Bcr(1) takes place together with the dynamical breakdown of the theory symmetry. 19 refs