Probing the muon $g-2$ with future beam dump experiments

TL;DR

Future beam dump experiments can effectively constrain or discover light $Z'$ particles responsible for the muon $g-2$ anomaly, especially when combined with neutrino scattering data, covering a broad parameter space.

Contribution

This paper demonstrates the potential of upcoming beam dump experiments to probe loop-induced couplings of a light $Z'$ to electrons in the context of muon $g-2$ anomaly explanations.

Findings

Beam dump experiments can set strong constraints on $Z'$ with loop-suppressed electron couplings.

Neutrino scattering experiments complement beam dump searches, especially if $Z'$ interacts strongly with neutrinos.

A large part of the $Z'$ parameter space can be tested in the near future.

Abstract

We consider the light $Z'$ explanation of the muon $g-2$ anomaly. Even if such a $Z'$ has no tree-level coupling to electrons, in general one will be induced at loop-level. We show that future beam dump experiments are powerful enough to place stringent constraints on$-$or discover$-$a $Z'$ with loop-suppressed couplings to electrons. Such bounds are avoided only if the $Z'$ has a large interaction with neutrinos, in which case the scenario will be bounded by ongoing neutrino scattering experiments. The complementarity between beam dump and neutrino scattering experiments therefore indicates that there are good prospects of probing a large part of the $Z'$ parameter space in the near future.