Abstract
A massive, but light, Abelian gauge boson is a well-motivated possible signature of physics beyond the standard model of particle physics. In this Letter, the search for the signal of such a gauge boson in electron-positron pair production at the spectrometer setup of the A1 Collaboration at the Mainz Microtron is described. Exclusion limits in the mass range of to , with a sensitivity in the squared mixing parameter of as little as 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 gauge boson.
- Received 22 April 2014
DOI:https://doi.org/10.1103/PhysRevLett.112.221802
© 2014 American Physical Society