Supersymmetric gauged U(1)Lμ−Lτ

Abstract

The gauged U (1)L µ−Lτ model can provide for additional contributions to the muon anomalous magnetic moment by means of a loop involving the Z gauge boson. However, the parameter space of such models is severely constrained if one combines the latest muon (g − 2) data with various neutrino experiments, such as neutrino trident production, ν − e and ν − q elastic scattering, etc. In a supersymmetric U (1)L µ−Lτ model, a larger region of parameter space opens up, thus enabling one to explore otherwise forbidden regions of parameter space in nonsupersymmetric models involving the new gauge coupling (gX ) and the mass of the Z gauge boson (M Z ) . We show that the minimal model with the minimal supersymmetric Standard Model (MSSM) field content is strongly disfavored from Z-boson decay and neutrino data. We also show that the nonminimal model with two extra singlet superfields can lead to correct neutrino masses and mixing involving both tree-level and one-loop contributions. We find that, in this model, both muon (g − 2) and neutrino data may be simultaneously explained in a parameter region consistent with experimental observations. In addition, we observe that the muon (g − 2) anomaly can be accommodated even with higher values of electroweak sparticle masses compared to the MSSM. Charged lepton-flavorviolating processes (like µ → eγ, τ → µγ, etc.) may have potentially large branching ratios in this scenario. Depending on the magnitude of the supersymmetry contribution to these processes, they may constrain hitherto unconstrained regions of the M Z − gX parameter space. However, we find that these branching fractions never exceed their upper bounds in a region where both muon (g − 2) and neutrino oscillation data can be simultaneously accommodated. arXiv:1805.04415v2 [hep-ph] 5 Nov 2018 c eLµÊ c µLτÊ c τĤuĤd U (1)L µ−Lτ 0 0 0 0 0 1 -1 -1 1 0 0

Supersymmetric gauged $$ \mathrm{U}{(1)}_{L_{\mu }-{L}_{\tau }} $$ model for electron and muon (g − 2) anomaly

“…A supersymmetric gauged U(1) Lµ−Lτ model requires at least two additional R-Parity even superfieldsη andη to be consistent with Z-boson decay observations and neutrino mixing texture [50]. Scalars corresponding to these U(1) Lµ−Lτ charged additional superfields, singlets under SM gauge symmetries and R-Parity even, acquire vacuum expectation values (VEVs) to break the additional gauge symmetry spontaneously.…”

“…The cancellation of chiral anomalies require these superfields to always have equal and opposite charge under the U(1) Lµ−Lτ symmetry. While R-Parity was not considered to be a global symmetry in [50], we work in a simplified scenario where R-Parity is conserved and the superpotential is given by…”

Reconciling dark matter, $$ {R}_{K^{\left(\ast \right)}} $$ anomalies and (g − 2)μ in an Lμ − Lτ scenario

“…Apart from being an anomaly free gauged U(1) extension, the L µ − L τ symmetry naturally violets the LFU between e and µ because the L µ − L τ charge of leptons are such that the corresponding new non-standard gauge boson couples only to µ(τ ) but not to e. This scenario was originally formulated by Volkas et al [77,78]. Thereafter, several variants of U(1) Lµ−Lτ model have been studied in the context of different phenomenological purposes: e.g., contribution of the U(1) Lµ−Lτ gauge boson to explain the (g − 2) µ anomaly [79][80][81][82][83][84][85][86], dark matter phenomenology [84,85,[87][88][89][90][91], generation of neutrino masses and mixing parameters [79,84,86,[92][93][94][95] etc.…”

Low-temperature enhancement of semi-annihilation and the AMS-02 positron anomaly

“…This symmetry is anomaly-free within the SM, and all of our new fermions are Dirac, so it can be gauged. A gauge symmetry of this form has been used to explain the structure of neutrino masses and mixings [79][80][81][82][83] and also has been invoked in other attempts to explain the positron excess [33,79,84].…”