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arXiv · 1604.07411

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

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

Recently a 6.8$\sigma$ anomaly has been reported in the opening angle and invariant mass distributions of $e^+ e^-$ pairs produced in $^8\text{Be}$ 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, $^8\text{Be}^* \to {}^8\text{Be} \, X$, and then decays through $X \to e^+ e^-$. The $X$ boson mediates a fifth force with a characteristic range of 12 fm and has milli-charged 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 3.6$\sigma$ discrepancy between the predicted and measured values of the muon's anomalous magnetic moment.

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Jonathan L. Feng, Bartosz Fornal, Iftah Galon, Susan Gardner, Jordan Smolinsky, Tim M. P. Tait, Philip Tanedo. 2016-04-25. Protophobic Fifth Force Interpretation of the Observed Anomaly in $^8$Be Nuclear Transitions. https://doi.org/10.1103/physrevlett.117.071803

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