Abstract
We present a search at the Jefferson Laboratory for new forces mediated by sub-GeV vector bosons with weak coupling to electrons. Such a particle can be produced in electron-nucleus fixed-target scattering and then decay to an pair, producing a narrow resonance in the QED trident spectrum. Using APEX test run data, we searched in the mass range 175–250 MeV, found no evidence for an reaction, and set an upper limit of . Our findings demonstrate that fixed-target searches can explore a new, wide, and important range of masses and couplings for sub-GeV forces.
- Received 12 August 2011
DOI:https://doi.org/10.1103/PhysRevLett.107.191804
© 2011 American Physical Society