Motivated by the fermion mass hierarchy, we study the phenomenology of two flavorful two-Higgs-doublet model (2HDM) scenarios. By virtue of the flavor or singular alignment ansatz, it is possible to link the mass of a subset of fermions to the vacuum expectation value (VEV) of a unique Higgs doublet and to simultaneously avoid flavor-changing-neutral-currents at tree level. We explicitly construct two models called Type A and B. There, either the top quark alone or all third generation fermions couple to the doublet with the larger VEV. The other fermions acquire their masses through the small VEV of the other doublet. Thus, more natural values for the Yukawa couplings can be obtained. The main differences between these models and conventional ones are studied, including a discussion of both their structure and phenomenological consequences. In particular, as distinctive deviations for the Yukawa couplings of the light fermions are predicted, we discuss possible tests at the LHC based on searches for $h\to J/\mathrm{\Psi }+\gamma$, $h\to \mu \mu$ and heavy scalar resonances decaying to muon pairs. We find that for a wide region of parameter space, this specific set of signatures can be used to distinguish among the new proposed types and the conventional ones.

• Received 21 October 2020
• Accepted 15 July 2021

DOI:https://doi.org/10.1103/PhysRevD.104.035018

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.

Published by the American Physical Society