Soft gluon–quark–antiquark emission in QCD hard scattering

Abstract We consider the radiation of a soft gluon ( g ) and quark–antiquark $$q{{\bar{q}}}$$ q ¯ pair in QCD hard scattering. In limit scattering amplitude has singular behaviour that is factorized controlled by current, which process-independent structure colour space. evaluate $$gq{{\bar{q}}}$$ g current at tree level for an arbitrary multiparton process. The irreducible correlation component includes strictly non-abelian terms also with abelian character. Analogous correlations appear photon–lepton–antilepton emission QED. squared produces dipole tripole interactions between hard-scattering partons. are odd under charge conjugation lead to asymmetry effects. specific applications processes two three partons, we discuss corresponding contributions. generalize our results cases QED mixed $$\times $$ × radiative corrections.