Observable manifestation of an electron-positron plasma created by the field of an optical laser

Abstract

Electron-positron vacuum pair creation in the quasi-periodic electric field of a standing wave is investigated for field strengths and frequencies corresponding to modern optical lasers using a quantum kinetic equation with a non-markovian source term. For a field E ∼ 5 · 1011 V/cm, the instantaneous quasiparticle electron-positron plasma is created which maximum density of order 1020cm−3. The mean value of the pair density per period <n> exceeds by many orders of magnitude the residual density nr which is taken over an integer number of field periods. The value <n> is proportional to the squared field intensity and does not depend on the frequency at ν ≪ m. Under conditions of presently available optical lasers with intensities exceeding I ∼ < 1020W/cm2, the mean number of created pairs in the volume of a wavelength cubed is about 107 which corresponds to 5 - 10 two-photon annihilation events per one laser pulse. The generated γ-quanta are suggested to be an observable signal of e+ e− pair vacuum creation in experiments with counter-propagating optical laser beams.