Formation of antihydrogen in excited states in antiproton-positronium collisions

The cross section for antihydrogen formation in excited 2s, 3s and 2p states is estimated using the Born approximation and compared with the cross section for antihydrogen formation in the ground state. These excited state cross sections are shown to be of comparable size to the ground state ones, thus increasing substantially the feasibility of antihydrogen formation in the laboratory. Partial s, p and d cross sections in the Born approximation are also given for the various processes.