Vacuum of the electroweak gauge theory in a strong magnetic field in A heat bath

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 Wienberg–Salam theory in a strong magnetic field in the thermostat. The estimation of the critical temperature $T_{\mathrm {cr}}$ which corresponds to the phase transition in the Weinberg–Salam theory is given in the one-loop approximation. It is shown how to define properly 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 $T=0$, $B>B_{\operatorname {cr}}^{(1)}$ takes place together with the dynamical breakdown of the theory symmetry.