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arXiv · 2105.13981

What is the scale of new physics behind the muon $g-2$?

Lukas Allwicher·Luca Di Luzio·Marco Fedele·Federico Mescia·Marco Nardecchia
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Abstract

We study the constraints imposed by perturbative unitarity on the new physics interpretation of the muon $g-2$ anomaly. Within a Standard Model Effective Field Theory (SMEFT) approach, we find that scattering amplitudes sourced by effective operators saturate perturbative unitarity at about 1 PeV. This corresponds to the highest energy scale that needs to be probed in order to resolve the new physics origin of the muon $g-2$ anomaly. On the other hand, simplified models (e.g.~scalar-fermion Yukawa theories) in which renormalizable couplings are pushed to the boundary of perturbativity still imply new on-shell states below 200 TeV. We finally suggest that the highest new physics scale responsible for the anomalous effect can be reached in non-renormalizable models at the PeV scale.

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Lukas Allwicher, Luca Di Luzio, Marco Fedele, Federico Mescia, Marco Nardecchia. 2021-05-28. What is the scale of new physics behind the muon $g-2$?. https://doi.org/10.1103/physrevd.104.055035

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