Search for light massive gauge bosons as an explanation of the $(g-2)_\mu$ anomaly at MAMI

TL;DR

This study searches for light massive gauge bosons at MAMI to explain the muon g-2 anomaly, setting exclusion limits that challenge their role in current discrepancies.

Contribution

It provides new experimental exclusion limits for light U(1) gauge bosons in the 40-300 MeV mass range, constraining theories beyond the Standard Model.

Findings

Excluded large parameter space where gauge bosons could explain muon g-2 discrepancy

Set sensitivity in mixing parameter down to 8×10^{-7}

Provided the most stringent limits in the specified mass range to date

Abstract

A massive, but light abelian U(1) gauge boson is a well motivated possible signature of physics beyond the Standard Model of particle physics. In this paper, the search for the signal of such a U(1) gauge boson in electron-positron pair-production at the spectrometer setup of the A1 Collaboration at the Mainz Microtron (MAMI) is described. Exclusion limits in the mass range of 40 MeV up to 300 MeV with a sensitivity in the mixing parameter of down to $\epsilon^2 = 8\times 10^{-7}$ are presented. A large fraction of the parameter space has been excluded where the discrepancy of the measured anomalous magnetic moment of the muon with theory might be explained by an additional U(1) gauge boson.