Light, beyond-The-standard-model particles X in the 1-100 MeV mass range can be produced in nuclear and hadronic reactions but would have to decay electromagnetically. We show that simple and well-understood low-energy hadronic processes can be used as a tool to study X production and decay. In particular, the pion capture process π-p→Xn→e+e-n can be used in a new experimental setup to search for anomalies in the angular distribution of the electron-positron pair, which could signal the appearance of dark photons, axionlike particles, and other exotic states. This process can be used to decisively test the hypothesis of a new particle produced in the Li7+p reaction. We also discuss a variety of other theoretically clean hadronic processes, such as p+D(T) fusion, as a promising source of X particles.
Bibliographical noteFunding Information:
We thank Drs. D. Bryman, J. Feng, and A. Papa for helpful discussions and useful communications. M. P. is grateful to Drs. B. Bastin, A. Coc and his colleagues at CSNSM Orsay, for productive discussions of possible X-boson search strategies. Research at Perimeter Institute is supported by the Government of Canada through Industry Canada and by the Province of Ontario through the Ministry of Economic Development and Innovation. C.-Y. C is supported by the DOE Grant No. DE-FG02-91ER40684 and the NSF Grant No. NSF-1740142. D. M. is supported by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada (NSERC) and TRIUMF which receives funding through a contribution agreement with the National Research Council of Canada (NRC). APPENDIX:
© 2019 authors. Published by the American Physical Society.