Models for the Electric Dipole Moment and Anomalous Magnetic Moment of the Tau Lepton

TL;DR

This paper proposes models that generate sizable electric dipole moments and anomalous magnetic moments for the tau lepton, predicting signals within future experimental sensitivity, thus providing benchmarks for new physics exploration.

Contribution

Introduction of two benchmark models that produce large tau EDM and g-2 signals, guiding future experimental searches for new physics effects.

Findings

Tau EDM predicted at ~10^{-19} e cm

Tau g-2 predicted at ~10^{-5}

Models are within future experimental reach

Abstract

The Belle II experiment and other ongoing and projected lepton facilities are expected to greatly enhance the sensitivity to the electric dipole moment (EDM) and anomalous magnetic moment ($g-2$) for the tau lepton, making it timely to explore models that predict these observables. We present a class of models that generate a sizable EDM and $g-2$ of the tau lepton via radiative tau mass generation. Two benchmark models with different hypercharge assignments are investigated. The first model contains neutral fermions and charged scalars. We find that the model can predict a large signal of the tau EDM, $d_{\tau} = \mathcal{O}(10^{-19}) \, e \, {\rm cm}$, and $g-2$, $a_{\tau} = \mathcal{O}(10^{-5})$, which are within the reach of future updates of their measurements. In contrast, the second model, containing a charged fermion and neutral scalars, yields a similar magnitude for the $g-2$ but predicts a comparatively smaller EDM signal. Our models serve as benchmarks for new physics generating sizable EDM and $g-2$ of the tau lepton.