Model for enhanced photonium production

We elucidate a mechanism for the production of photonium, a set of resonances of the e+e- system. Due to their small, possibly vanishing, elastic width, the free space formation of these states is inhibited and external fields may substantially enhance their production. We develop a model for enhanced production based upon a three body mechanism involving a positron and a correlated pair of atomic electrons. Very strong sensitivity to the electron pair correlation is obtained. Decreasing this correlation by a factor of two over a range appropriate to inner shell orbitals of high Z atoms increases the photonium production cross sections by eight orders of magnitude. For fixed correlation length, a sharp peak is found in the production cross section as the incoming positron energy is varied through a region near threshold for photonium production via this three body mechanism. (orig.)