Laser field effect on β decays of nuclei

The effect of a laser field on β-decays of nuclei is considered when the field intensity F is small compared to the characteristic field F0 defined by the decay energy I and electron mass, F << F0 = 2I(2mI)sup(1/2)/eh/2π, and when the frequency of the field satisfies the condition h/2πω < or approximately I. The decay probability is an asymptotic expansion in powers of (F/F0)2 and in small terms which are non-analytic for F=0. The expansion is similar to that for a constant field with coefficients which depend on the frequency as a+b(ω/I)2+..., where a, b approximately 1. The leading probability correction terms are analytic with respect to charge and therefore can be reproduced by perturbation theory. The probability structure found is specific for processes which occur in the absence of a field as long as the field frequency is small compared to the characteristic kinetic energy of the light charged particles, and the field intensity is insufficient to alter significantly the energy during the formation of the process