Electron and muon $g-2$ anomalies in general flavour conserving two Higgs doublets models

Abstract

In general two Higgs doublet models (2HDMs) without scalar flavour changing neutral couplings (SFCNC) in the lepton sector, the electron, muon and tau interactions can be decoupled in a robust framework, stable under renormalization group evolution. In this framework, the breaking of lepton flavour universality (LFU) goes beyond the mass proportionality, opening the possibility to accommodate in a simple manner a different behaviour among charged leptons. We analyze simultaneously the electron and muon (g − 2) anomalies in the context of these general flavour conserving models in the leptonic sector (g FC). We consider two different models, I-g FC and II-g FC, in which the quark Yukawa couplings coincide, respectively, with the ones in type I and in type II 2HDMs. We find two types of solutions that fully reproduce both (g − 2) anomalies, and which are compatible with experimental constraints from LEP and LHC, from LFU, from flavour and electroweak physics, and with theoretical constraints in the scalar sector. In the first type of solution, all the new scalars have masses in the 1-2.5 TeV range, the vacuum expectation values (vevs) of both doublets are quite similar in magnitude, and both anomalies are dominated by two loop Barr-Zee contributions. This solution appears in both models. There is a second type of solution, where one loop contributions are dominant in the muon anomaly, all new scalars have masses below 1 TeV, and the ratio of vevs is in the range 10-100. The second neutral scalar H is the lighter among the new scalars, with a mass in the 210-390 GeV range while the pseudoscalar A is the heavier, with a mass in the range 400-900 GeV. The new charged scalar H ± is almost degenerate either with the scalar or with the pseudoscalar. This second type of solution only appears in the I-g FC model. Both solutions require the soft breaking of the Z 2 symmetry of the Higgs potential.

Heavy singly charged Higgs bosons and inverse seesaw neutrinos as origins of large $(g-2)_{e,μ}$ in two higgs doublet models

“…Some two Higgs doublet models (THDM) can provide sizeable two-loop contributions to ∆a µ arising from new SU (2) L Higgs doublets [56][57][58][59][60][61], where some of them require rather light masses of new neutral and/or charged Higgs boson masses at few hundred GeV.…”

An explanation of experimental data of $(g-2)_{e,μ}$ in 3-3-1 models with inverse seesaw neutrinos

“…Many models beyond the SM (BSM) have been constructed to explain the experimental data of (g − 2) µ,e , such as models adding vector-like lepton multiplets [8][9][10][11][12][13][14][15][16][17], leptoquarks [18], both neutral and charged Higss bosons as SU (2) L singlets [19]. Some two Higgs doublet models can give large two-loop contributions to ∆a µ from new SU (2) L Higgs doublets [20][21][22], where some of them require rather light masses of new neutral and/or charged Higgs bosons at few hundred GeV.…”

Power-aligned 2HDM: a correlative perspective on $(g-2)_{e,μ}$

“…), with three independent entries ζ i , a simultaneous explanation of both ∆a e and ∆a µ anomalies can still be achieved [22,23]. Such a general A2HDM (gA2HDM) [24,25], nevertheless, enlarges the degrees of freedom of the model parameters and makes the simultaneous explanation of the ∆a e,µ anomalies non-correlative.…”

“…Within the power-aligned 2HDM (pA2HDM) proposed here, instead, the resolution of ∆a e,µ can alleviate the constraints from these leptonic precision observables, because, on the one hand, the new Higgs mass spectrum is now quasi-degenerate, rendering some cancellations among the quantum corrections, and, on the other hand, the power enhancement in the electron and muon Yukawa entries necessary for the ∆a e,µ explanation increases the tau Yukawa coupling at a speed slower than that in the linear alignment. Furthermore, being distinguishable from the gA2HDM that addresses the ∆a e,µ anomalies in a non-correlative manner [22,23], the pA2HDM predicts an interesting correlation between the two anomalies, which can be therefore tested by future precise measurements [58][59][60].…”

“…where ζ f are flavor-universal proportionality parameters. In the gA2HDM [22][23][24][25], on the other hand, the parameters ζ f are promoted to be diagonal matrices with three independent entries. In both of these two cases, the absence of tree-level FCNC is guaranteed by the ability of simultaneous diagonalization of Y 1,2 , as they commute with each other.…”