The muon magnetic moment in the 2HDM: complete two-loop result

Abstract

Abstract:We study the 2HDM contribution to the muon anomalous magnetic moment a µ and present the complete two-loop result, particularly for the bosonic contribution. We focus on the Aligned 2HDM, which has general Yukawa couplings and contains the type I, II, X, Y models as special cases. The result is expressed with physical parameters: three Higgs boson masses, Yukawa couplings, two mixing angles, and one quartic potential parameter. We show that the result can be split into several parts, each of which has a simple parameter dependence, and we document their general behavior. Taking into account constraints on parameters, we find that the full 2HDM contribution to a µ can accommodate the current experimental value, and the complete two-loop bosonic contribution can amount to (2 · · · 4) × 10 −10 , more than the future experimental uncertainty.

A call for new physics: The muon anomalous magnetic moment and lepton flavor violation

“…There are caveats in our reasoning which are worth pointing out: There are two-loop diagrams which also yield sizable contributions for some regions of the parameter space involving quarks and gauge bosons, as already pointed out in [354][355][356] and discussed further in [181,[357][358][359] which may affect our results;…”

Muon g−2 in the 2HDM: Maximum results and detailed phenomenology

“…[22][23][24][25][26][27] studied the so-called type X (or leptonspecific) model, and the authors of Refs. [28][29][30] the more general (flavor-)aligned model [31,32]. In all these cases it was shown that a light pseudoscalar A boson with large couplings to leptons is viable and could explain Eq.…”

“…Earlier studies [22][23][24][25][26][27][28][29][30] and our later considerations show that a μ can be promisingly large for small M A and large ζ l and ζ u , so we focus on this scenario. Our study can be regarded as a generalization of Refs.…”

“…The bosonic two-loop contributions a B μ computed in Ref. [30] depend on a large number of additional parameters: the physical Higgs masses M H , M H AE ; the mixing angle c βα ; tan β; and the Higgs potential parameters λ 1 and λ 6;7 . In the present section we provide an overview of the influence of these parameters, constraints on their values, and update the analysis of Ref.…”

“…The authors of Ref. [30] computed the 2HDM contributions fully at the two-loop level, including all bosonic contributions (from Feynman diagrams without closed fermion loop). Prior to that, the author of Ref.…”