CP Violation in Three-Body Chargino Decays

TL;DR

This paper calculates CP violation rate asymmetries in three-body chargino decays within supersymmetry, revealing potential asymmetries of around 10% that could be observable under certain conditions.

Contribution

It provides the first detailed computation of CP asymmetries in specific three-body chargino decays, considering resonant Higgs contributions and their impact on CP violation.

Findings

Rate asymmetries up to 10% can occur in some decay channels.

Resonant Higgs contributions significantly enhance CP asymmetries.

Results are consistent with existing low-energy experimental bounds.

Abstract

CP violation in supersymmetry can give rise to rate asymmetries in the decays of supersymmetric particles. In this work we compute the rate asymmetries for the three-body chargino decays \tilde\chi^\pm_2 \to \tilde\chi^\pm_1 HH, \tilde\chi^\pm_2 \to \tilde\chi^\pm_1 ZZ, \tilde\chi^\pm_2 \to \tilde\chi^\pm_1 W^+ W^- and \tilde\chi^\pm_2 \to tilde\chi^\pm_1 ZH. Each of the decays contains contributions mediated by neutral Higgs bosons that can possibly go on shell. Such contributions receive a resonant enhancement; furthermore, the strong phases required for the CP asymmetries come from the widths of the exchanged Higgs bosons. Our results indicate that the rate asymmetries can be relatively large in some cases, while still respecting a number of important low-energy bounds such as those coming from B meson observables and electric dipole moments. For the parameters that we consider, rate asymmetries of order 10% are possible in some cases.