Large CP Phases and the Cancellation Mechanism in EDMs in SUSY, String and Brane Models

TL;DR

The paper demonstrates a scaling behavior of EDMs in SUSY models, showing how cancellation mechanisms can keep EDMs small across parameter space, with applications to string and brane models with large CP phases.

Contribution

It introduces a simple scaling property of EDMs in SUSY models and explores how this can be used to identify regions with suppressed EDMs, including in string-inspired models.

Findings

EDMs obey an approximate scaling under parameter transformations.

A trajectory in parameter space can be generated where EDM cancellations occur.

Large CP phases are compatible with EDM constraints via the cancellation mechanism.

Abstract

We show that EDMs obey a simple approximate scaling under the transformation $m_0\to \lambda m_0,m_{{1/2}}\to \lambda m_{{1/2}}$ in the large $\mu$ region when $\mu$ itself obeys the same scaling, ie., $\mu \to \lambda \mu$. In the scaling region the knowledge of a single point in the MSSM parameter space where the cancellation in the EDMs occur allows one to generate a trajectory in the $m_0-m_{{1/2}}$ plane where the cancellation mechanism holds and the EDMs are small. We illustrate these results for MSSM with radiative electro-weak symmetry breaking constraints. We also discuss a class of D brane models based on Type IIB superstring compactifications which have non-universal phases in the gaugino mass sector and allow large CP violating phases consistent with the EDM constraints through the cancellation mechanism. The scaling in these D brane models and in a heterotic string model is also discussed.