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Updated: May 26, 2026

Setting Limits on Supersymmetry Using Simplified Models
Published on: November 15, 2013
Search for a new gauge boson in electron-nucleus fixed-target scattering by the APEX experiment
S Abrahamyan1, Z Ahmed, K Allada
1Yerevan Physics Institute, Yerevan 375036, Armenia.
Abstract:
We present a search at the Jefferson Laboratory for new forces mediated by sub-GeV vector bosons with weak coupling α' to electrons. Such a particle A' can be produced in electron-nucleus fixed-target scattering and then decay to an e + e- 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 A'→ e+ e- reaction, and set an upper limit of α'/α ~/= 10(-6). Our findings demonstrate that fixed-target searches can explore a new, wide, and important range of masses and couplings for sub-GeV forces.
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