Laser-assisted antihydrogen formation

Abstract

Laser-assisted antihydrogen $(\overline{\mathrm{H}})$ formation cross sections (differential and total) for collisions of antiprotons with positronium (Ps) are studied in the framework of the eikonal approximation for two geometries, when the field polarization is parallel $({\ensuremath{\Vert}}^{L})$ or perpendicular $({\ensuremath{\perp}}^{r})$ to the incident Ps momentum. The variations of the $\overline{\mathrm{H}}$ formation cross sections with respect to the field strength and the laser photon energy are studied for the multiphoton (absorption and emission) processes. The contribution of the atomic (both Ps and $\overline{\mathrm{H}}$) dressing terms to the enhancement of the $\overline{\mathrm{H}}$ formation cross section is studied for both the geometries (${\ensuremath{\Vert}}^{L}$ and ${\ensuremath{\perp}}^{r}$). The most important prediction from the present work is the enhancement of the field-free (FF) $\overline{\mathrm{H}}$ formation cross sections particularly at lower incident energies when the system $(\mathrm{Ps}+\overline{p})$ is irradiated by a single mode, linearly polarized laser, the enhancement being more pronounced for a wider range of incident energy in the ${\ensuremath{\perp}}^{r}$ geometry than in the ${\ensuremath{\Vert}}^{L}$ one.