Probing a dark photon using rare leptonic kaon and pion decays

Abstract

Rare leptonic kaon and pion decays $K^{+}({\pi }^{+})\to {\mu }^{+}{\nu }_{\mu }{e}^{+}{e}^{-}$ can be used to probe a dark photon of mass $\mathcal{O}(10)$~MeV, with the background coming from the mediation of a virtual photon. This is most relevant for the 16.7-MeV dark photon proposed to explain a 6.8$\sigma$ anomaly recently observed in ${}^8$Be transitions by the Atomki Collaboration. We evaluate the reach of future experiments for different scenarios of how the dark photon couples with the standard model particles, and show that a great portion of the preferred 16.7-MeV dark photon parameter space can be decisively probed. We also show the use of angular distributions to further distinguish the signal from the background.

17 pages, 7 figures

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Cited by in corpus (6)

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• Atomki Anomaly in Family-Dependent $U(1{)}^{\prime }$ Extension of the Standard Model
• Is There a Sign of New Physics in Beryllium Transitions?
• Searching for dark photons in hyperon decays
• Search for a massless dark photon in ${\Lambda }_c^{+}\to p{\gamma }^{\prime }$ decay
• Kaon decays shedding light on massless dark photons