An Unfamiliar Way to Generate the Hierarchy of Standard Model Fermion Masses

Author:

S. Baek, J. Kersten, P. Ko, L. Velasco-Sevilla

Keyword:

High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph)

journal:

CQUeST-2023-0724, KIAS-P23038

date:

2023-09-13 16:00:00

Abstract

While the properties of the observed Higgs boson agree with the Standard Model predictions, the hierarchy of fermion masses lacks an explanation within the model. In this work, we propose a fresh approach to this problem, involving a different Higgs doublet responsible for each quark mass. We construct a model with a gauged, non-anomalous $U(1)$ family symmetry that fixes which fermion couples to which doublet with an $\mathcal{O}(1)$ Yukawa coupling. The hierarchy of masses is generated by the hierarchy of vacuum expectation values of the Higgs fields. The model generically predicts a light, weakly coupled pseudoscalar. We verify that the model satisfies constraints from flavour changing neutral currents, Higgs phenomenology and electroweak precision tests.