Multiple soft gluon radiation in parton processes

Abstract

A previously introduced recursive calculational method is used to analyse the systematics of multiple soft gluon emission in multi-parton processes. Factorizaton properties in subamplitudes are discussed. The case of soft gluons with equal helicities leads to simple expressions. Explicit formulae for double soft gluon emission are given. The hard partons in the processes are gluons, a qq̄ pair with or without a vector boson. The special assumption of strong ordering of soft gluon momenta transforms the general expression into the ones known from the literature. For pure gluonic processes a new relation between the subamplitudes is derived.