Muon g-2 and CP violation in MSSM

TL;DR

This paper examines how CP violation constraints impact the MSSM explanation of the muon g-2 anomaly, highlighting the need for specific SUSY breaking mechanisms or fine-tuning of CP phases.

Contribution

It identifies scenarios within MSSM where muon g-2 is explained via chargino or bino loops and analyzes the severe constraints from electron EDM experiments on CP phases.

Findings

Electron EDM constraints require CP phases to be smaller than 2-3×10^{-5}.

Specific SUSY breaking mechanisms are necessary to naturally explain muon g-2 without fine-tuning.

A tuning of order 10^{-5} is needed to cancel CP phases in general MSSM models.

Abstract

We study the constraints of the CP violation in the muon $g-2$ preferred region of the minimal supersymmetric standard model assuming a universal slepton masses within first two generations. We present two particular scenarios where the $g-2$ anomaly is predicted within 2 $\sigma$ level mainly through the chargino loop or the bino loop. We found that for both cases the electron EDM experiment already highly constrained the CP phase of the parameters: either the Arg[$\mu M_1]$ or Arg[$\mu M_2]$ should be smaller than $\mathcal O$(2-3)$\times10^{-5}$. If the muon $g-2$ anomaly is explained by the MSSM, a particular SUSY breaking mechanism is needed to guarantee the small CP phase of SUSY parameters. Otherwise, a tuning of $\mathcal O(10^{-5})$ is needed to cancel the phase in a general CP violated SUSY model.