Effective hamiltonian for the electric dipole moment of the neutron

Abstract

Recently it has been shown that, in extensions of the minimal standard model, the effective hamiltonian for the electric dipole moment of the neutron contains the dimension-six operator [Tr GGG˜] (with G the gluon field strength tensor and G˜ its dual) and that the effects of this operator are not suppressed by light (up, down and strange) quark masses. We note that at the weak-scale this effective hamiltonian also contains the dimension-six operator m_bb̅σ_μvG˜^σvb (with b the bottom quark field and m_b its mass) whose effects do not vanish in the chiral limit. We calculate in models with weveral Higgs doublets the influence of this operator on low energy physics, showing that when the heavy bottom quark is integrated out, it induces the operator [TrGGG̅].