An explanation for the muon and electron g \u2212 2 anomalies and dark matter

Kai-Feng Chen,Kei Yagyu,Cheng-Wei Chiang

doi:10.1007/jhep09(2020)119

Abstract

We propose simple models with a flavor-dependent global U(1)ℓ and a discrete ℤ2 symmetries to explain the anomalies in the measured anomalous magnetic dipole moments of muon and electron, (g − 2)μ,e, while simultaneously accommodating a dark matter candidate. These new symmetries are introduced not only to avoid the dangerous lepton flavor-violating decays of charged leptons, but also to ensure the stability of the dark matter. Our models can realize the opposite-sign contributions to the muon and electron g − 2 via one-loop diagrams involving new vector-like leptons. Under the vacuum stability and perturbative unitarity bounds as well as the constraints from the dark matter direct searches and related LHC data, we find suitable parameter space to simultaneously explain (g − 2)μ,e and the relic density. In this parameter space, the coupling of the Higgs boson with muons can be enhanced by up to ∼ 38% from its Standard Model value, which can be tested in future collider experiments.

Highlights

In order to accommodate both g − 2 anomalies simultaneously, a characteristic flavordependent structure is called for
We propose simple models with a flavor-dependent global U(1) and a discrete Z2 symmetries to explain the anomalies in the measured anomalous magnetic dipole moments of muon and electron, (g − 2)μ,e, while simultaneously accommodating a dark matter candidate
To explain the muon and electron g − 2 anomalies and the dark matter data, we have proposed a new model whose symmetry is enlarged to have a global U(1) and a discrete Z2 symmetries and whose particle content is extended with two vector-like leptons and the inert scalar singlet and doublet fields

Summary

Dark matter phenomenology

It is worth mentioning that in the Inert Doublet Model (IDM), another solution of the DM mass to satisfy the relic density may exist in a TeV region when the mass splitting among the Z2-odd scalar particles is small, typically less than 10 GeV [43]. In such a scenario, DM dominantly annihilates into a pair of weak gauge bosons whose annihilation cross section decreases by O(1/m2DM), while the annihilation into the Higgs bosons is highly suppressed due to small Higgs-DM couplings. The scenario of having a fermionic DM in our model is ruled out

Collider phenomenology

Findings

Conclusions