Abstract
In a two Higgs doublet model with extra Yukawa couplings, we assess the new physics contributions to charged lepton electric dipole moment. We focus especially on muon (and tau) EDM where in the coming decade several experiments — Muon g-2, J-PARC and PSI (and Belle II) — will push sensitivities down by several orders of magnitude. With the working assumption that extra Yukawa couplings are analogous to SM ones in strength and taking exotic scalar masses in sub-TeV range, we find that μ and τ EDM can be enhanced to values larger than new physics scenarios that scale with lepton mass. The main effect comes from the flavor-conserving extra top coupling ρtt via well-known two-loop diagrams. Deviating from our working assumption, if the muon g − 2 anomaly arises from the one-loop diagram, driven by singly enhanced lepton flavor violating ρτμ coupling, it can also induce rather large muon EDM, accessible at upcoming experiments.
Highlights
Already in 2013, ACME provided the best upper limit on eEDM, |de| < 8.7×10−28 e cm [13]
With the working assumption that extra Yukawa couplings are analogous to SM ones in strength and taking exotic scalar masses in sub-TeV range, we find that μ and τ EDM can be enhanced to values larger than new physics scenarios that scale with lepton mass
Deviating from our working assumption, if the muon g − 2 anomaly arises from the one-loop diagram, driven by singly enhanced lepton flavor violating ρτμ coupling, it can induce rather large muon EDM, accessible at upcoming experiments
Summary
Before we proceed to the specifics, let us lay out the framework of the model. The Yukawa interactions in g2HDM are given by [5, 28],. It is worth pointing out that with cγ 0.1 our assumptions ρμμ O(λμ) and ρττ O(λτ ) are compatible with the latest data on di-muon and di-tau decays of the h boson, respectively These processes provide access to the strength and phase of extra Yukawa couplings. There are additional subdominant diagrams related to charged Higgs loops which depend on trilinear Higgs couplings The expressions of these are given in appendix A. We ignore them since our scope is to cover effects from Yukawa interactions of eq (2.1) These contribution can be important in models with CPV scalar potentials, or 2HDM models with softly broken Z2 symmetry, where large contributions such as in eq (3.8) are negligible From figure 4 and for our benchmarks, dτ can reach ∼ 10−23 e cm, but again falls short of Belle II sensitivity
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