Grand Unification Scale CP Violating Phases And The Electric Dipole Moment

TL;DR

This paper investigates CP violating phases in supergravity GUT models and their implications for electric dipole moments, highlighting the fine-tuning issues and the impact of model variations on these phases.

Contribution

It analyzes the behavior of CP violating phases in minimal and non-minimal supergravity GUT models, especially their evolution from the GUT scale to the electroweak scale.

Findings

Quadratic soft breaking phase must be small unless tanβ<3

EDM data constrains CP phases at the electroweak scale

Fine-tuning of phases is required at the GUT scale for larger tanβ

Abstract

The question of CP violating phases in supersymmetry and electric dipole moments (EDMs) is considered within the framework of supergravity grand unification (GUT) models with a light ($\stackrel{<}{\sim}$1 TeV) mass spectrum. In the minimal model, the nearness of the t-quark Landau pole automatically suppresses the t-quark cubic soft breaking phase at the electroweak scale. However, current EDM data require the quadratic soft breaking phase to be small at the electroweak scale unless tan$\beta$ is small (tan$\beta\stackrel{<}{\sim}$3), and the EDM data combined with the requirement of electroweak symmetry breaking require this phase to be both large and highly fine tuned at the GUT scale unless tan$\beta$ is small. Non minimal models are also examined, and generally show the same behavior.