VACUUM OF THE ELECTROWEAK GAUGE-THEORY IN A STRONG MAGNETIC-FIELD IN A HEAT BATH

Expressions are obtained for the thermodynamic potential of a gas of e lectrically charged vector bosons in a magnetic field and the effectiv e potential of the Weinberg-Salam theory in a strong magnetic field in a heat bath. In the single-loop approximation, an estimate is obtaine d for the value of the critical temperature T-cr corresponding to the phase transition in the Weinberg-Salam theory in a magnetic field. It is shown that it is possible to determine correctly the total probabil ity for production of a W+W- boson pair from the vacuum by an ultrastr ong magnetic field in a heat bath, and an expression is obtained for t his probability. It is argued that in the Weinberg-Salam theory the re storation of the spontaneously broken symmetry at T=0, B>B-cr((1)) is simultaneously accompanied by dynamical symmetry breaking of the theor y.