Positronium Formation in Positron-Hydrogen Scattering

A pair of coupled equations describing positron-hydrogen scattering in the energy range where only positronium in its ground state may be formed is solved numerically. The equations, unlike others previously derived, are local to lowest order. The effects of the polarizability of both hydrogen and positronium are included in various ways. The $s$-wave phase shift at threshold is close to that obtained previously by solution of the nonlocal equations when no polarization is included, and is dramatically improved when polarization of both hydrogen and positronium is included. The positronium formation cross section is about 40 times smaller than the Born approximation. These are the only comparisons with previous work available.