Browsing by Author "King, S. F."

We study an extended 2 Higgs doublet model (2HDM) in which the Standard Model (SM) Yukawa interactions are forbidden due to a global U(1)₀ 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.

Wediscuss Z mediated flavor changing neutral currents within a model where the hierarchical quark and lepton masses are explained via a fourth vectorlike family, together with a scalar sector consisting of two Higgs doublets augmented by a gauge singlet scalar field that spontaneously breaks an extra global Uð1Þ0 symmetry. The Z mediated flavor violating interactions arise from the mixings between the SM fermions and the vectorlike fermions, where the mixing is discussed in an analytic approximation and also exactly numerically. We first discuss charged lepton flavor violating (CLFV) τ → μγ, τ → 3μ and Z → μτ decays and find that they cannot significantly constrain the masses of charged vectorlike leptons. However, the 790 GeVmassboundarising from collider searches onvectorlike lepton doublets can set further constraints on the model parameter space. We also consider rare t → cZ decays as well as unitarity violation in the CKM mixing in order to constrain the quark sector of the model under consideration.