How to Compute in Practice the Energy Carried Away by Soft Photons to All Orders in alpha

摘要

Based on Yennie, Frautschi and Suura's results, an analytic expression is given for the differential cross section with respect to the total energy carried away by soft photons in any collision or decay process. This expression only involves Lorentz invariant dot-products between the particle 4-moments. It is valid to all orders in the fine structure constant alpha . (ERA citation 13:019823)