Supersymmetry, CP Violation and the Neutron Electric Dipole Moment

Experimentally observable consequences of supersymmetry may involve CP-violating processes, such as the neutron electric dipole moment d_n, that are generically enhanced in supersymmetric models. We investigate the contributions to d_n both for very low and for moderate scales of supersymmetry breaking. In particular, we consider the contribution of the dimension-six CP-violating operator proposed recently by Weinberg. We show that this operator cannot be supersymmetrised and hence its contribution is suppressed in models with only very weakly broken super-symmetry. For more realistic scales of supersymmetry breaking, this operator does contribute appreciably to d_n, but the dominant contributions turn out to be those of the dimension-five quark electric dipole moment and the quark color electric dipole moment operators.