QED cascades induced by circularly polarized laser fields

The results of Monte-Carlo simulations of electron-positron-photon cascades initiated by slow electrons in circularly polarized fields of ultrahigh strength are presented and discussed. Our results confirm previous qualitative estimations [A. M. Fedotov et al., Phys. Rev. Lett. 105, 080402 (2010)] of the formation of cascades. This sort of cascade has revealed a new property of restoration of energy and dynamical quantum parameter due to acceleration of electrons and positrons by the field. This may become a dominating feature of laser-matter interactions at ultrahigh intensities. Our approach incorporates radiation friction acting on individual electrons and positrons.