Euler-Heisenberg-Schwinger Lagrangian for nonadiabatically varying fields

Abstract

Nonperturbative particle production in external variable fields is important in astrophysics. Although a wide range of techniques exists for calculating production rate, none of them can handle exactly the case of a strongly inhomogeneous field. Here, an electric field with an abrupt switch-on is considered. First, a standard semiclassical technique is used. Then, a scattering problem approach to this case is developed and time-dependent corrections to the effective Euler-Heisenberg-Schwinger Lagrangian are calculated.