title: Stokes phenomenon and schwinger vacuum pair production in time-dependent laser pulses.
abstract: Particle production due to external fields (electric, chromoelectric, or gravitational) requires evolving an initial state through an interaction with a time-dependent background, with the rate being computed from a Bogoliubov transformation between the in and out vacua. When the background fields have temporal profiles with substructure, a semiclassical analysis of this problem confronts the full subtlety of the Stokes phenomenon: WKB solutions are only local, while the production rate requires global information. We give a simple quantitative explanation of the recently computed [Phys. Rev. Lett. 102, 150404 (2009)10.1103/PhysRevLett.102.150404] oscillatory momentum spectrum of e^{+}e^{-} pairs produced from vacuum subjected to a time-dependent electric field with subcycle laser pulse structure. This approach also explains naturally why for spinor and scalar QED these oscillations are out of phase.
authors.affiliation: Department of Physics, University of Connecticut, Storrs, Connecticut 06269-3046, USA.
authors.forename: Cesim K
authors.initials: CK
authors.lastname: Dumlu
authors.forename: Gerald V
authors.initials: GV
authors.lastname: Dunne