Schwinger mechanism of electron-positron pair production by the field of optical and X-ray lasers in vacuum

The probability W of e + e −-pair production in vacuum by an intense time-varying electric field created by optical or X-ray laser is calculated. Two characteristic regions γ≪1 and γ≫1 of adiabaticity parameter γ are considered. With an increase in γ and on passing from monochromatic radiation to a finite laser pulse, the probability W increases sharply (for the same field intensity). The dependence of the probability W and the electron and positron momentum spectrum on the pulse shape is discussed (the dynamic Schwinger effect).