Multichannel scattering and annihilation in the positron hydrogen system

摘要

A problem to account for the direct electron-positron annihilation in positron-hydrogen scattering above the positronium formation threshold has been resolved within the time independent formalism. On the basis of the generalized optical theorem, the annihilation cross section is fully determined by scattering amplitudes. This allows to perform the analytic separation of the contribution of the positronium formation effect from the overall annihilation cross section. The rest determines the direct annihilation cross section.