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 gamma << 1 and gamma >> 1 of adiabaticity parameter gamma are considered. With an increase in gamma 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). (C) 2001 MAIK Nauka/Interperiodica.