Weak Triplet Models of Neutrino Magnetic Moments
Abstract
Experimental limits on neutrino magnetic moments remain several orders of magnitude above the predictions of the Standard Model; therefore, any future detection would provide unambiguous evidence for new physics. In models with Dirac neutrinos, however, mechanisms that enhance the magnetic moment typically generate excessively large neutrino masses. Recently, it has been argued that in frameworks where neutrinos mix with weak-triplet Dirac fermions, the magnetic moment can be decoupled from the neutrino mass. In this work, we revisit this possibility and show that sizable enhancements remain highly nontrivial to realize naturally. We demonstrate that, although the minimal realization allows the magnetic moment to be decoupled from the neutrino mass, obtaining an observable enhancement requires a delicate adjustment of the model parameters. Moreover, in extended scenarios, the decoupling no longer persists: the magnetic moment and neutrino mass become intrinsically linked, such that attempts to enhance the former inevitably induce large contributions to the latter.
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BibTeX
@misc{fajfer2026weak,
title = {{Weak Triplet Models of Neutrino Magnetic Moments}},
author = {Svjetlana Fajfer and Shaikh Saad},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2605.19544},
eprint = {2605.19544},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.19544},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Weak Triplet Models of Neutrino Magnetic Moments
AU - Svjetlana Fajfer
AU - Shaikh Saad
PY - 2026
DA - 2026/09/26
PB - arXiv
DO - 10.48550/arxiv.2605.19544
UR - https://arxiv.org/abs/2605.19544
AB - Experimental limits on neutrino magnetic moments remain several orders of magnitude above the predictions of the Standard Model; therefore, any future detection would provide unambiguous evidence for new physics. In models with Dirac neutrinos, however, mechanisms that enhance the magnetic moment typically generate excessively large neutrino masses. Recently, it has been argued that in frameworks where neutrinos mix with weak-triplet Dirac fermions, the magnetic moment can be decoupled from the neutrino mass. In this work, we revisit this possibility and show that sizable enhancements remain highly nontrivial to realize naturally. We demonstrate that, although the minimal realization allows the magnetic moment to be decoupled from the neutrino mass, obtaining an observable enhancement requires a delicate adjustment of the model parameters. Moreover, in extended scenarios, the decoupling no longer persists: the magnetic moment and neutrino mass become intrinsically linked, such that attempts to enhance the former inevitably induce large contributions to the latter.
ER -