Enhancing lepton flavour violation in the supersymmetric inverse seesaw beyond the dipole contribution

TL;DR

This paper demonstrates that in the supersymmetric inverse seesaw model, the $Z$-penguin contribution to lepton flavor violation can dominate and reach future experimental sensitivities, unlike in minimal models.

Contribution

It shows that the non-minimal particle content enhances $Z$-penguin effects, making certain lepton flavor violating processes observable at upcoming experiments.

Findings

$Z$-penguin dominates LFV in the inverse seesaw.

Enhanced $ ext{Br}(\mu o 3e)$ and $ ext{mu-e}$ conversion within future reach.

Non-decoupling behavior of $Z$-penguin similar to Higgs decays.

Abstract

In minimal supersymmetric models the $Z$-penguin usually provides sub-dominant contributions to charged lepton flavour violating observables. In this study, we consider the supersymmetric inverse seesaw in which the non-minimal particle content allows for dominant contributions of the $Z$-penguin to several lepton flavour violating observables. In particular, and due to the low-scale (TeV) seesaw, the penguin contribution to, for instance, $\Br(\mu \to 3e)$ and $\mu-e$ conversion in nuclei, allows to render some of these observables within future sensitivity reach. Moreover, we show that in this framework, the $Z$-penguin exhibits the same non-decoupling behaviour which had previously been identified in flavour violating Higgs decays in the Minimal Supersymmetric Standard Model.