Sauter-Schwinger Effect for Colliding Laser Pulses.

Via a combination of analytical and numerical methods, we study electron-positron pair creation by the electromagnetic field A(t,r)=[f(ct-x)+f(ct+x)]e_{y} of two colliding laser pulses. Employing a generalized Wentzel-Kramers-Brillouin approach, we find that the pair creation rate along the symmetry plane x=0 (where one would expect the maximum contribution) displays the same exponential dependence as for a purely time-dependent electric field A(t)=2f(ct)e_{y}. The prefactor in front of this exponential does also contain corrections due to focusing or defocusing effects induced by the spatially inhomogeneous magnetic field.