Induced multi-gluon couplings and the neutron electric dipole moment

Abstract

Weinberg recently pointed out that purely gluonic operators that violate CP, like in particular the dimension six operator GG G can be induced via electroweak radiative corrections; such an operator would generate a non-vanishing value for the neutron electric dipole moment. We generalize that discussion by analyzing various classes of models for CP violation. We also present an alternative procedure for estimating the size of the relevant hadronic matrix element. We find that this yields considerably smaller values; this comes on top of the recent observation that QCD radiative corrections greatly reduce the weight of the GG G operator. Nevertheless this operator can still have some phenomenological impact, in particular if there exists an extended Higgs sector containing CP violation.