Neutrino masses and magnetic moments of electron and muon in the Zee Model

Abstract

We explore parameter space in the Zee Model to resolve the long-standing tension of the electron and muon anomalous magnetic moment (AMM). The model comprises a second Higgs doublet and a charged singlet at electroweak scale and generates Majorana neutrino masses at one-loop level; the neutral partner of the SU(2)L doublet contributes to the AMM of electron and muon via one loop and two-loop corrections. We propose two minimal flavor structures that can explain these anomalies while fitting the neutrino oscillation data. We find that the neutral Higgs resides in the mass range of roughly 10–300 GeV or 1–30 GeV, depending on the flavor structures. The model is consistent with constraints from colliders, electroweak precision data, and lepton flavor violation. To be comprehensive, we examine the constraints from the electric dipole moment (EDM) and find a region of parameter space that gives a sizable contribution to muon EDM while simultaneously giving corrections to muon AMM. In addition to the light scalar, the two charged scalars with masses as low as 100 GeV can induce nonstandard neutrino interactions εee as large as 8%, potentially hinting at new physics. We also investigate the projected capability of future lepton colliders to probe the currently allowed parameter space consistent with both electron and muon AMMs via direct searches in the ℓ+ℓ− → ℓ+ℓ−(H → ℓ+ℓ−) channel.

Zee-model predictions for lepton flavor violation

“…The µ term in the Lagrangian will induce a mixing of η + with the charged scalar contained in H 2 ; we denote the mixing angle by φ and the two mass eigenstates by h + and H + , see Ref. [14] for details. Finally, Y is an arbitrary complex Yukawa matrix while f is antisymmetric in flavor space.…”

$W$ boson mass shift and muon magnetic moment in the Zee model

“…Pink and purple regions are obtained from e + e − → µ + µ − H searches at BABAR [16] and LHC [17]. The black dash-dotted line on the left plot shows the projected sensitivity reach on Yµµ from direct searches in the µ + µ − → µ + µ − H → µ + µ − channel at the 3 TeV Muon Collider assuming L = 1 ab −1 [18]. The pink (purple) shaded region assumes the BR(H → µµ) = 1 (0.5) with the purple dotted line BR(H → µµ) = 1.…”

“…The important constraints on the Yukawa couplings Y and the masses of the doublet Higgs are cLFV from radiative decay i → j γ [2,19], trilepton decays [20], muonium-antimuonium oscillation [21], as well as various experimental constraints obtained from e + e − → µ + µ − H searches at BABAR [16] and LHC [17]. Moreover, LEP [22] puts a strong constraint with an upper limit of about 30 GeV [18] on the scalar mass associated with Y eµ to explain ∆a µ , obtained via searches e + e − → e ± µ ∓ (H → e ± µ ∓ ). There are also constraints from cLFV and universality in i → j νν on f ij couplings, which are relatively relaxed compared to Y ij in our scenario.…”

“…3 (for a detailed analysis see Ref. [18]). There are no dedicated searches for the neutral scalar fields decaying into the τ + µ − sector by ATLAS and CMS.…”

Muon and electron $g-2$ anomalies in a flavor conserving 2HDM with an oblique view on the CDF $M_W$ value

“…The specific model considered, the so-called I-g FC 2HDM is a 2HDM without tree level scalar flavor changing neutral couplings (SFCNC): in the quark sector it is a type I 2HDM while in the lepton sector it is a general flavor conserving model. The existence of these two anomalies has been addressed in a variety of scenarios, including models with extra Higgs doublets [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38], models with other scalar extensions [39][40][41][42][43][44][45][46][47][48] and supersymmetric models [49][50][51][52][53]. There are also plenty of studies with other approaches such as leptoquarks, vector-like fermions or extra gauge bosons, among others [54][55][56][57][58][59][60][61][62][63][64][65]…”