Positronium Decay in a Circular Polarized Laser Field

We calculate the lifetime of both the o-Ps and the p-Ps positronium annihilation decay P s →γγ in the strong circular polarized laser field. We take a strategy of the factorization to separate the efects caused by the Coulomb interaction and the strong laser field interaction. It is factorized in the time direction but not in the space direction. Our results show that in the laser with long wavelength and high intensity, the lifetimes of those Ps states are dramatically increased. For CO2 laser with 10 μm wavelength and 1013W/cm2intensity, lifetime of the spin-single positronium is increased by 108times. Our result is consistent with those obtained by solving the Sch¨odinger equation. This efect may be useful for the high harmonic generation(HHG) efects provided with the Ps [Phys. Rev. Lett. 70(1993) 774; Phys. Rev. Lett. 93(2004) 013601].