On Schwinger mechanism of e+e- pair production from vacuum by the field of optical and X-ray lasers

The probability W of e(+) e(-) pair production under the action of intensive electric field created by optical or X-ray laser is calculated. Two characteristic regions, gamma much less than 1, gamma much greater than 1, of adiabaticity parameter gamma are considered. It is shown that with gamma increase, as well as when turning over from monochromatic radiation to a laser pulse of finite time duration, the probability W sharply increases (at the same field intensity). The dependence of the probability W and of the momentum spectrum of electrons and positrons on the pulse shape is discussed (the dynamical Schwinger effect). (C) 2002 Elsevier Science B.V. All rights reserved.