Electric Dipole Moments in Natural Supersymmetry

TL;DR

This paper examines how recent and future experimental limits on electric dipole moments constrain the parameter space of natural supersymmetry, highlighting the importance of CP-violating phases and their implications for model building.

Contribution

It provides new formulas for two-loop fermion EDMs applicable to various models and analyzes their impact on natural SUSY parameter constraints.

Findings

Two-loop effects of stops and charginos restrict CP phases in natural SUSY.

Future EDM measurements will further constrain SUSY parameter space.

Small CP phases are required, intensifying the CP problem in natural SUSY.

Abstract

We discuss electric dipole moments (EDMs) in the framework of CP-violating natural supersymmetry (SUSY). Recent experimental results have significantly tightened constraints on the EDMs of electrons and of mercury, and substantial further progress is expected in the near future. We assess how these results constrain the parameter space of natural SUSY. In addition to our discussion of SUSY, we provide a set of general formulas for two-loop fermion EDMs, which can be applied to a wide range of models of new physics. In the SUSY context, the two-loop effects of stops and charginos respectively constrain the phases of $A_t \mu$ and $M_2 \mu$ to be small in the natural part of parameter space. If the Higgs mass is lifted to 125 GeV by a new tree-level superpotential interaction and soft term with CP-violating phases, significant EDMs can arise from the two-loop effects of $W$ bosons and tops. We compare the bounds arising from EDMs to those from other probes of new physics including colliders, $b \to s \gamma$, and dark matter searches. Importantly, improvements in reach not only constrain higher masses, but require the phases to be significantly smaller in the natural parameter space at low mass. The required smallness of phases sharpens the CP problem of natural SUSY model building.