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Models for the electric dipole moment and anomalous magnetic moment of the tau lepton

Yuichiro Nakai ^1,2, Yoshihiro Shigekami ³, Peng Sun ^1,2, and Zhihao Zhang ^1,2

¹Tsung-Dao Lee Institute, Shanghai Jiao Tong University, No. 1 Lisuo Road, Pudong New Area, Shanghai 201210, China
²School of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
³School of Physics, Henan Normal University, Xinxiang, Henan 453007, China

Phys. Rev. D 113, 035001 – Published 2 February, 2026

DOI: https://doi.org/10.1103/rnrt-9gjy

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. In this work, we study a class of models in which the tau mass is generated radiatively. As a result, sizable EDM and $g - 2$ of the tau lepton arise as a natural consequence of the radiative mass generation mechanism at the electroweak scale. We present two benchmark models with different hypercharge assignments. The first model contains neutral fermions and charged scalars. We find that the model can predict a large signal of the tau EDM, $d_{τ} = O (10^{- 19}) e cm$ , and $g - 2$ , $a_{τ} = O (10^{- 5})$ , 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 but different sign for $g - 2$ , and predicts a comparatively smaller EDM signal. Our models serve as well-motivated benchmarks for new physics scenarios in which radiative tau mass generation leads to sizable tau dipole moments.

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Phys. Rev. D 113, 035001– Published 2 February, 2026

Vol. 113, Iss. 3 — 1 February 2026

Received 12 October 2025
Accepted 5 January 2026

DOI: https://doi.org/10.1103/rnrt-9gjy

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

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Models for the electric dipole moment and anomalous magnetic moment of the tau lepton

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