Fermion mass hierarchies from vectorlike families with an extended 2HDM and a possible explanation for the electron and muon anomalous magnetic moments

We study an extended 2 Higgs doublet model (2HDM) in which the Standard Model (SM) Yukawa
interactions are forbidden due to a global Uð1Þ0 symmetry, but may arise via mixing with vectorlike
families. In this model, the hierarchical structure of Yukawa couplings of quarks and leptons in the SM
arises from the heavy masses of the fourth and fifth vectorlike families. Within this model, we consider
various nonstandard contributions to the electron and muon anomalous magnetic moments. We first
consider the W exchange at one-loop level, consistent with the μ → eγ constraint, and show that it yields a
negligible contribution to both electron and muon anomalous magnetic moments. We then consider Higgs
scalar exchange, together with vectorlike leptons, at one-loop level and show that it is possible to have
nonstandard contributions to the electron and muon anomalous magnetic moments within the 1σ constraint
of certain experiments. We present some benchmark points for both the muon and the electron anomalies,
together with some numerical scans around these points, which indicate the mass regions of the Higgs
scalars of the 2HDM in this scenario.