EDM constraints on flavored CP-violating phases

TL;DR

This paper analyzes how different CP-violating phases in the MSSM with MFV affect electric dipole moments, identifying dominant contributions and assessing experimental constraints, with implications for future EDM measurements.

Contribution

It classifies CP-violating phases in the MSSM with MFV, identifies their dominant contributions to EDMs, and explores constraints and naturality of soft-breaking terms beyond MFV.

Findings

Flavor-blind phases dominate EDM contributions.

Next-generation EDM experiments will tightly constrain flavor-blind phases.

Neutrino sector phases have negligible impact on EDMs.

Abstract

The CP-violating phenomenology of the MSSM with Minimal Flavor Violation (MFV) in the lepton sector is revisited. To this end, the most general parametrizations of the slepton soft-breaking terms are constructed assuming a seesaw mechanism of type I. After a critical reassessment of how the CP-symmetry is broken within the MFV framework, all possible CP-violating phases are introduced. From the strong hierarchy of their contributions to the Electric Dipole Moments (EDMs), these phases are split into three classes: flavor-blind, flavor-diagonal and flavor off-diagonal. In particular, the phases from the neutrino sector belong to the last class; they start to contribute only at the second order in the mass-insertion approximation and have thus a negligible effect. It is then shown that to each class of phases corresponds a unique largely dominant term in the MFV expansion. Numerically, for a realistic range of MSSM and neutrino parameters, such that B(mu --> e gamma) does not exceed its experimental bound, the three types of phases are found to be allowed by the current bound on the electron EDM, though the next generation of experiments should constrain tightly the flavor-blind phase. Finally, we relax the MFV hypothesis and show how in the general MSSM, the MFV operator basis can be used to judge of the naturality of the slepton soft-breaking terms.