Laser-assisted charge transfer in positronium collisions with protons and antiprotons*

We study the process of laser-assisted charge transfer in collisions of positronium atoms with protons (antiprotons) with formation of Rydberg hydrogen (antihydrogen) atoms

by the use of Classical Trajectories Monte Carlo simulations of Ps-p dynamics in a linearly polarized infrared field. We do not observe a drastic enhancement of the cross sections similar to that predicted before in laser-assisted electron bremsstrahlung [1] and electron recombination [2] since in the present charge transfer process the Coulomb focusing

effect is absent. Still we see a substantial enhancement up to a factor of three in the energy range between 10^-4 and 0.1 eV for the field of intensity between 10 MW/cm² and 10 GW/cm². The effect depends weakly on the orientation of the incident Ps velocity relative to the field polarization vector. Rydberg states of the produced hydrogen

atoms whose orbits are close to circular can survive against ionization by laser field and decay spontaneously to lower states. This is favorable for spectroscopic studies of antihydrogen atoms.

[1] H. B Ambalampitiya and I. I. Fabrikant, Phys. Rev. A 99, 063404 (2019).

[2] I. I. Fabrikant and H. B Ambalampitiya, Phys. Rev. A 101, 053401 (2020).