Testing the CP-violating MSSM in stau decays at the LHC and ILC

TL;DR

This paper investigates CP violation in stau decays within the MSSM at the LHC and ILC, identifying significant asymmetries that could reveal CP phases in supersymmetry.

Contribution

It introduces a method to measure CP asymmetries in stau decays sensitive to MSSM CP phases, with potential for detection at collider experiments.

Findings

Asymmetries over 70% are achievable with strong stau mixing.

Detectable CP asymmetries are possible at the LHC.

The study motivates experimental efforts to probe SUSY CP phases.

Abstract

We study CP violation in the two-body decay of a scalar tau into a neutralino and a tau, which should be probed at the LHC and ILC. From the normal tau polarization, a CP asymmetry is defined which is sensitive to the CP phases of the trilinear scalar coupling parameter $A_\tau$, the gaugino mass parameter $M_1$, and the higgsino mass parameter $\mu$ in the stau-neutralino sector of the Minimal Supersymmetric Standard Model. Asymmetries of more than 70% are obtained in scenarios with strong stau mixing. As a result, detectable CP asymmetries in stau decays at the LHC are found, motivating further detailed experimental studies for probing the SUSY CP phases.