Factorization and soft-gluon divergences in isolated-photon cross sections
Factorization and soft-gluon divergences in isolated-photon cross sections
We study the production of isolated photons in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation and give the proof of the all-order factorization of the collinear singularities. These singularities are absorbed in the standard fragmentation functions of partons into a photon, while the effects of the isolation are consistently included in the short-distance cross section. …