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

Jonathan L. Feng, Bartosz Fornal, Iftah Galon, Susan Gardner, Jordan Smolinsky, Tim M.P. Tait, Philip Tanedo

Research output: Contribution to journalArticlepeer-review

161 Scopus citations


Recently a 6.8σ anomaly has been reported in the opening angle and invariant mass distributions of e+e- pairs produced in Be8 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, Be∗8→Be8 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.

Original languageEnglish
Article number071803
JournalPhysical Review Letters
Issue number7
StatePublished - Aug 11 2016

Bibliographical note

Publisher Copyright:
© 2016 American Physical Society.

ASJC Scopus subject areas

  • General Physics and Astronomy


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