Electron EDM as a Sensitive Probe of PeV Scale Physics

TL;DR

This paper analyzes how electron electric dipole moments (EDMs) can detect physics at PeV scales, surpassing collider capabilities, by exploring supersymmetric and non-supersymmetric contributions and their interference effects.

Contribution

It provides a detailed quantitative analysis of electron EDM as a probe of high-scale physics, including the effects of vectorlike generations and CP phases, revealing new cancellation phenomena.

Findings

Electron EDM can probe mass scales from tens of TeV to PeV.

Interference effects cause the EDM to vanish and reappear as slepton mass varies.

High-scale physics effects dominate EDM beyond collider reach.

Abstract

We give a quantitative analysis of the electric dipole moments as a probe of high scale physics. We focus on the electric dipole moment of the electron since the limit on it is the most stringent. Further, theoretical computations of it are free of QCD uncertainties. The analysis presented here first explores the probe of high scales via electron EDM within MSSM where the contributions to the electric dipole moment (EDM) arise from the chargino and the neutralino exchanges in loops. Here it is shown that the electron EDM can probe mass scales from tens of TeV into the PeV range.The analysis is then extended to include a vectorlike generation which can mix with the three ordinary generations. Here new CP phases arise and it is shown that the electron EDM now has not only a supersymmetric contribution from the exchange of charginos and neutralinos but also a non-supersymmetric contribution from the exchange of W and Z bosons. It is further shown that the interference of the supersymmetric and the non-supersymmetric contribution leads to the remarkable phenomenon where the electron EDM as a function of the slepton mass first falls and become vanishingly small and then rises again as the slepton mass increases This phenomenon arises as a consequence of cancellation between the SUSY and the non-SUSY contribution at low scales while at high scales the SUSY contribution dies out and the EDM is controlled by the non-SUSY contribution alone. The high mass scales that can be probed by the EDM are far in excess of what accelerators will be able to probe. The sensitivity of the EDM to CP phases both in the SUSY and the non-SUSY sectors are also discussed.