A Custodial Symmetry for Muon g-2

Understand

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.