Muon g-2 Anomaly and Dark Leptonic Gauge Boson

TL;DR

This paper examines the muon g-2 anomaly and explores a dark leptonic gauge boson model based on gauged lepton number, which remains viable despite recent experimental constraints that exclude the dark photon model.

Contribution

It introduces the U(1)_L gauge boson as an alternative to the dark photon, showing it can explain muon g-2 while evading current experimental bounds.

Findings

U(1)_L gauge boson remains compatible with muon g-2 data.

Recent neutrino flux experiments constrain but do not exclude the U(1)_L model.

Dark photon models are now practically excluded by latest data.

Abstract

One of the major motivations to search for a dark gauge boson of MeV-GeV scale is the long-standing muon g-2 anomaly. Because of active searches such as fixed target experiments and rare meson decays, the muon g-2 favored parameter region has been rapidly reduced. With the most recent data, it is practically excluded now in the popular dark photon model. We overview the issue and investigate a potentially alternative model based on the gauged lepton number or U(1)_L. The muon g-2 favored parameter region of the U(1)_L survives all the constraints that were critical in the dark photon case, yet it is disfavored by the new constraints from the large flux neutrino experiments.