The magnetic moment of the τ lepton is an interesting quantity that is potentially sensitive to physics beyond the Standard Model. Electroweak gauge invariance implies that a heavy new physics contribution to it takes the form of an operator which involves the Higgs boson, implying that rare Higgs decays are able to probe the same physics as aτ. We examine the prospects for rare Higgs decays at future high energy lepton (electron or muon) colliders, and find that such a project collecting a few ab−1 would be able to advance our understanding of this physics by roughly a factor of 10 compared to the expected reach of the high luminosity LHC.
@article{arxiv.1810.09570,
title = {The $\tau$ Magnetic Dipole Moment at Future Lepton Colliders},
author = {Jessica N. Howard and Arvind Rajaraman and Rebecca Riley and Tim M. P. Tait},
journal= {arXiv preprint arXiv:1810.09570},
year = {2018}
}