Small SUSY phases in string-inspired supergravity

TL;DR

It is found that the SUSY phases can be suppressed by a small factor governing the breakdown of the approximate Peccei-Quinn symmetries nonlinearly realized for the moduli superfields that participate in supersymmetry breaking.

Abstract

In supersymmetric models, there are new CP violating phases which, if unsuppressed, would give a too large neutron electric dipole moment. We examine the possibility of small SUSY phases in string-inspired supergravity models in which supersymmetry is broken by the auxiliary components of the dilaton and moduli superfields. It is found that the SUSY phases can be suppressed by a small factor governing the breakdown of the approximate Peccei Quinn symmetries nonlinearly realized for the moduli superfields that participate in supersymmetry breaking. In many cases, the symmetry breaking factors are exponentially small for moderately large values of the moduli, leading to small phase values in a natural way.