Higgs--Flavon Mixing and $h\to \mu \tau$

Abstract

ATLAS and CMS have reported an excess in the flavor violating decay of the Higgs boson, $h\to \mu \tau$. We show that this result can be accommodated through a mixing of the Higgs with a flavon, the field responsible for generating the Yukawa matrices in the lepton sector. We employ a version of the Froggatt-Nielsen mechanism at the electroweak scale, with only the leptons and the flavon transforming non--trivially under the corresponding symmetry group. Non--observation of charged lepton flavor violation (LFV) in other processes imposes important constraints on the model, which we find to be satisfied in substantial regions of parameter space.

Comments: 19 pages, 5 figures, to appear in JHEP