NUCLEAR BETA-DECAY AND PHOTOPRODUCTION OF E(-) PAIRS IN INTENSE ELECTROMAGNETIC-FIELDS WITH A COMPLEX CONFIGURATION()E()

The effect of an intense electromagnetic field formed by the superposi tion of a constant magnetic field and a laser-type field on nuclear be ta-decay and on pair production by two gamma-rays with different polar izations is studied. Time integral representations are obtained for th e total probabilities of these processes without restrictions on the s trengths of the fields making up the configuration. Despite the differ ent nature of these reactions, in the nonrelativistic limit these expr essions contain similar dependences on the field characteristics and t he differences reduce to different power-law singularities in the beha vior of the integrands at zero. At low fields, complete asymptotic exp ansions of the probabilities of these processes, including perturbatio n theory terms and oscillatory field contributions, are obtained in te rms of parameters characterizing the fields. It is shown that the osci llatory corrections can be enhanced owing to the effect of a combinati on external field. The analysis of the probabilities of the various pr ocesses given here in terms of nonlinear functions of the field is ill ustrated by numerical calculations and graphs. (C) 1998 American Insti tute of Physics.