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Selection rules for charged lepton flavor violating processes from residual flavor groups

Lorenzo Calibbi ^1,*, Claudia Hagedorn ^2,†, Michael A. Schmidt ^3,‡, and James Vandeleur ^3,§

¹School of Physics, Nankai University, Tianjin 300071, China
²Instituto de Física Corpuscular, Universitat de València—CSIC, Parc Científic, Catedrático José Beltrán 2, 46980 Paterna, Spain
³Sydney Consortium for Particle Physics and Cosmology, School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia

^*Contact author: calibbi@nankai.edu.cn
^†Contact author: claudia.hagedorn@ific.uv.es
^‡Contact author: m.schmidt@unsw.edu.au
^§Contact author: james.vandeleur@unsw.edu.au

Phys. Rev. D 112, 075031 – Published 17 October, 2025

DOI: https://doi.org/10.1103/b6gz-c1c9

Abstract

We systematically investigate the possible phenomenological impact of residual flavor groups in the charged lepton sector. We consider all possible flavor charge assignments for Abelian residual symmetries up to $Z_{8}$ . The allowed flavor structures of operators in Standard Model effective field theory (up to dimension six) lead to distinctive and observable patterns of charged lepton flavor violating processes. We illustrate the relevance of such selection rules displaying the current bounds on and the future sensitivities to the new physics scale. These results demonstrate, in particular, the importance and discriminating power of searches for lepton flavor violating $τ$ lepton decays and muonium to antimuonium conversion.

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Phys. Rev. D 112, 075031– Published 17 October, 2025

Vol. 112, Iss. 7 — 1 October 2025

Received 10 June 2025
Accepted 8 August 2025

DOI: https://doi.org/10.1103/b6gz-c1c9

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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Selection rules for charged lepton flavor violating processes from residual flavor groups

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