A Custodial Symmetry for Muon g-2

Abstract

We discuss the recent results on the muon anomalous magnetic moment in the context of new physics models with light scalars. We propose a model in which the one-loop contributions to g-2 of a scalar and a pseudoscalar naturally cancel in the massless limit due to the symmetry structure of the model. This model allows to interpolate between two possible interpretations. In the first interpretation, the results provide a strong evidence of the existence of new physics, dominated by the positive contribution of a CP-even scalar. In the second one, supported by the recent lattice result, the data provides a strong upper bound on new physics, specifically in the case of (negative) pseudoscalar contributions. We emphasize that tree-level signatures of the new degrees of freedom of the model are enhanced relative to conventional explanations of the discrepancy. As a result, this model can be tested in the near future with accelerator-based experiments and possibly also at the precision frontier.

13 pages, 2 figures

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• Self-consistent extraction of spectroscopic bounds on light new physics
• From axion quality and naturalness problems to a high-quality ${\mathbb{Z}}_N$ QCD relaxion
• Towards an independent determination of muon g-2 from muonium spectroscopy
• Probing CP Violation in Photon Self-Interactions with Cavities
• The Muon Magnetic Moment and Physics Beyond the Standard Model
• The Elusive Muonic WIMP
• Improved bounds on ultralight scalar dark matter in the radio-frequency range
• Implications of recent ${\left(g-2\right)}_{\mu }$ measurements for MeV-GeV dark sector searches
• Muon g-2 from Millicharged Hidden Confining Sector
• Searching for hadronic scale baryonic and dark forces at $(g-2{)}_{\mu }$'s lattice-vs-dispersion front