Spectra of Particles from Laser-Induced Vacuum Decay
  The spectrum of electrons and positrons originating from vacuum decay occurring in the collision of two non-colinear laser pulses is obtained. It displays high energy, highly-collimated particle bunches traveling in a direction separate from the laser beams. This result provides an unmistakable signature of the vacuum decay phenomenon and could suggest a new avenue for development of high energy electron and/or positron beams. 
Lance Labun and Johann Rafelski
hep-ph physics.plasm-ph