Prospects for a flavour violating $Z^{\prime }$ explanation of $\Delta a_{\mu ,e}$

Abstract

The apparent tensions emerging from the comparison of experimental data of the anomalous magnetic moments of the muon and electron to the Standard Model predictions ($\Delta a_{\mu ,e}$) could be interpreted as a potential signal of New Physics. Models encompassing a light vector boson have been known to offer a satisfactory explanation to $\Delta a_{\mu }$, albeit subject to stringent experimental constraints. Here we explore a minimal extension of the Standard Model via a leptophilic vector boson $Z^{\prime }$, under the hypothesis of strictly flavour-violating couplings of the latter to leptons. The most constraining observables to this ad-hoc construction emerge from lepton flavour universality violation (in $Z$ and $\tau$ decays) and from rare charged lepton flavour violating transitions. Once these are accommodated, one can saturate the tensions in $\Delta a_{\mu }$, but $\Delta a_e$ is predicted to be Standard Model-like. We infer prospects for several observables, including leptonic $Z$ decays and several charged lepton flavour violating processes. We also discuss potential signatures of the considered $Z^{\prime }$ at a future muon collider, emphasising the role of the ${\mu }^{+}{\mu }^{-}\to {\tau }^{+}{\tau }^{-}$ forward-backward asymmetry as a key probe of the model.

36 pages, 15 figures, v3: minor changes, few clarifications added, results and conclusions unchanged, matches version published in EPJC

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Cited by in corpus (8)

• The Muon Magnetic Moment and Physics Beyond the Standard Model
• Conceptual Design of the Muonium-to-Antimuonium Conversion Experiment (MACE)
• Anomalous and axial Z' contributions to g-2
• Revisiting for maximal flavor violating $Z_{e\mu }^{{}^{\prime }}$ and its phenomenology constraints
• Collider probe of heavy additional Higgs bosons solving the muon $g-2$ and dark matter problems
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• LFV decays in a 3-4-1 model with minimal inverse seesaw neutrinos