Can \epsilon'/\epsilon be supersymmetric?

TL;DR

This paper reevaluates the potential size of supersymmetric contributions to '/, suggesting they could be larger than previously thought and possibly dominate the observed '/ value, with implications for neutron EDM experiments.

Contribution

It challenges the common assumption of small supersymmetric contributions to '/ by considering more general models and parameters, showing larger possible effects.

Findings

Supersymmetric contribution to '/ can be around 3^{-3} for squark mass 500 GeV.

Supersymmetric effects could dominate the measured '/ value.

Neutron electric dipole moment may be within experimental reach.

Abstract

The possible supersymmetric contribution to \epsilon'/\epsilon has been generally regarded small in the literature. We point out, however, that this is a result based on specific assumptions, such as universal scalar mass, and in general needs not to be true. Based on a general situation, (1) hierarchical quark Yukawa matrices protected by flavor symmetry, (2) generic dependence of Yukawa matrices on Polonyi/moduli fields as expected in many supergravity/superstring theories, (3) Cabibbo rotation originating from the down-sector, and (4) phases of order unity, we find the typical supersymmetric contribution to \epsilon'/\epsilon to be order 3x10^-3 for m_{\tilde{q}} = 500 GeV. It is even possible that the supersymmetric contribution dominates in the reported KTeV value \epsilon'/\epsilon = (28 \pm 4.1)x10^-4. If so, the neutron electric dipole moment is likely to be within the reach of the currently planned experiments.