SELF-ACTION OF INTENSE ELECTROMAGNETIC-RADIATION IN AN ELECTRON-POSITRON VACUUM

An analysis is done of the effects of self-action of intense coherent electromagnetic radiation in an electron-positron vacuum that is in ho mogeneous electric and magnetic fields. A modified version of the Heis enberg-Euler theory, in which the Lagrangian incorporates terms with f ield derivatives, is used to take into account vacuum dispersion. The nonphysical branch of the solutions of the dispersion equation is excl uded by a transition to a quasioptical equation for the slowly varying field envelope, an equation that describes the propagation of radiati on with allowance for diffraction, spatial-temporal dispersion, and va cuum nonlinearity. The existence of dark solitons (with an intensity g ap) in the vacuum is shown to be present. Finally, self-focusing of ra diation in a vacuum is demonstrated and the critical self-focusing pow er is determined. (C) 1998 American Institute of Physics.