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Open Access Publications from the University of California

Protophobic Fifth-Force Interpretation of the Observed Anomaly in Be-8 Nuclear Transitions

  • Author(s): Feng, JL
  • Fornal, B
  • Galon, I
  • Gardner, S
  • Smolinsky, J
  • Tait, TMP
  • Tanedo, P
  • et al.

Recently a 6.8σ anomaly has been reported in the opening angle and invariant mass distributions of e^{+}e^{-} pairs produced in ^{8}Be nuclear transitions. The data are explained by a 17 MeV vector gauge boson X that is produced in the decay of an excited state to the ground state, ^{8}Be^{*}→^{8}Be X, and then decays through X→e^{+}e^{-}. The X boson mediates a fifth force with a characteristic range of 12 fm and has millicharged couplings to up and down quarks and electrons, and a proton coupling that is suppressed relative to neutrons. The protophobic X boson may also alleviate the current 3.6σ discrepancy between the predicted and measured values of the muon's anomalous magnetic moment.

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