Search for dark matter decay of the free neutron from the UCNA experiment: N→χ+e+e-

UCNA Collaboration

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

It has been proposed recently that a previously unobserved neutron decay branch to a dark matter particle (χ) could account for the discrepancy in the neutron lifetime observed in experiments that use two different measurement techniques. One of the possible final states discussed includes a single χ along with an e+e- pair. We use data from the UCNA (Ultracold Neutron Asymmetry) experiment to set limits on this decay channel. Coincident electron-like events are detected with ∼4π acceptance using a pair of detectors that observe a volume of stored ultracold neutrons. The summed kinetic energy (Ee+e-) from such events is used to set limits, as a function of the χ mass, on the branching fraction for this decay channel. For χ masses consistent with resolving the neutron lifetime discrepancy, we exclude this as the dominant dark matter decay channel at 5σ level for 100<Ee+e-<644keV. If the χ+e+e- final state is not the only one, we set limits on its branching fraction of <10-4 for the above Ee+e- range at >90% confidence level.

Original languageEnglish
Article number052501
JournalPhysical Review C
Volume97
Issue number5
DOIs
StatePublished - May 21 2018

Funding

We are grateful for helpful discussions with B. Grinstein. This work is supported in part by the US Department of Energy, Office of Nuclear Physics (DE-FG02-08ER41557, DE-SC0014622, DE-FG02-97ER41042) and the National Science Foundation (NSF-1002814, NSF-1005233, NSF-1102511, NSF-1205977, NSF-1306997, NSF-1307426, NSF-1506459, and NSF-1615153). We gratefully acknowledge the support of the LDRD program (20110043DR) and the AOT division of the Los Alamos National Laboratory.

Fingerprint

Dive into the research topics of 'Search for dark matter decay of the free neutron from the UCNA experiment: N→χ+e+e-'. Together they form a unique fingerprint.

Cite this