Article
Search for Dark Matter Decay of the Free Neutron from the UCNA Experiment: n → χ + e^+e^−
Physical Review C
(2018)
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 χalong 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.
Keywords
- Dark Matter,
- Decay,
- Free Neutron,
- UCNA Experiment
Publication Date
May 21, 2018
DOI
10.1103/PhysRevC.97.052501
Publisher Statement
©2018 American Physical Society. Authors have the nonexclusive right to post the APS-prepared version of the article to an institutional repository. This document was originally published in Physical Review C.
Citation Information
Xiaohui Sun, Edith Adamek, Bruno Allgeier, Matthias A. Blatnik, et al.. "Search for Dark Matter Decay of the Free Neutron from the UCNA Experiment: n → χ + e^+e^−" Physical Review C Vol. 97 Iss. 5 (2018) p. 52501 ISSN: 2469-9985 Available at: http://works.bepress.com/robert-pattie/5/