RELATIVISTIC VERSION OF THE IMAGINARY-TIME FORMALISM

A relativistic version of the quasiclassical imaginary-time formalism is developed. It permits calculation of the tunneling probability of r elativistic particles through potential barriers, including barriers l acking spherical symmetry. Application of the imaginary-time formalism to concrete problems calls for finding subbarrier trajectories which are solutions of the classical equations of motion, but with an imagin ary time (and thus cannot be realized in classical mechanics). The ion ization probability of an s level, whose binding energy can be of the order of the rest energy, under the action of electric and magnetic fi elds of different configuration is calculated using the imaginary-time formalism. Besides the exponential factor, the Coulomb and pre-expone ntial factors in the ionization probability are calculated. The Hamilt onian approach to the tunneling of relativistic particles is described briefly. Scrutiny of the ionization of heavy atoms by an electric fie ld provides an additional argument against the existence of the ''Unru h effect.'' (C) 1998 American Institute of Physics. [S1063-7761(98)004 09-0].