MSSM Predictions for the Electric Dipole Moment of the $^{199}$Hg Atom

TL;DR

This paper calculates how CP-violating phases in the MSSM affect the electric dipole moment of the $^{199}$Hg atom, providing new constraints on these phases with fewer uncertainties than neutron EDM calculations.

Contribution

It introduces a precise calculation of the MSSM's CP-violating effects on the mercury atom's EDM, offering stronger constraints on MSSM parameters than previous neutron or electron EDM limits.

Findings

Mercury EDM constraints are more restrictive in some MSSM regions.

Calculated Schiff moments are less affected by QCD uncertainties.

Combined EDM measurements limit MSSM CP-violating phases effectively.

Abstract

The Minimal Supersymmetric Standard Model can possess several CP-violating phases beyond the conventional Cabibo-Kobayashi-Maskawa phase. We calculate the contribution of these phases to T-violating nuclear forces. These forces induce a Schiff moment in the $^{199}$Hg nucleus, which is strongly limited by experiments aimed at the detection of the electric dipole moment of the mercury atom. The result for $d_{Hg}$ is found to be very sensitive to the CP-violating phases of the MSSM and the calculation carries far fewer QCD uncertainties than the corresponding calculation of the neutron EDM. In certain regions of the MSSM parameter space, the limit from the mercury EDM is stronger than previous constraints based on either the neutron or electron EDMs. We present combined constraints from the mercury and electron EDMs to limit both CP-violating phases of the MSSM. We also present limits in mSUGRA models with unified gaugino and scalar masses at the GUT scale.