EPJ Web Conf.
Volume 219, 2019International Workshop on Particle Physics at Neutron Sources (PPNS 2018)
|Number of page(s)||5|
|Section||Tests of Gravity, Dark Matter and Dark Energy|
|Published online||13 December 2019|
Search for neutron dark decay: n → χ + e+e−
1 W.K. Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125, USA
2 Department of Physics, Indiana University, Bloomington, Indiana 47408, USA
3 Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
4 Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
5 Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
6 Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708, USA
7 Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, USA
8 Department of Physics and Center for Experimental Nuclear Physics and Astrophysics, University of Washington, Seattle, Washington 98195, USA
9 Institut Laue-Langevin, 38042 Grenoble Cedex 9, France
10 Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China
11 Department of Physics, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
12 Cyclotron Institute, Texas A&M University, College Station, Texas 77843, USA
13 Department of Physics, Idaho State University, Pocatello, Idaho 83209, USA
14 Department of Physics and Astronomy and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
a e-mail: firstname.lastname@example.org
Published online: 13 December 2019
In January, 2018, Fornal and Grinstein proposed that a previously unobserved neutron decay branch to a dark matter particle (χ) could account for the discrepancy in the neutron lifetime observed in two different types of experiments. 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 (UCNs). We use the timing information of coincidence events to select candidate dark sector particle decays by applying a timing calibration and selecting events within a physically-forbidden timing region for conventional n → p + e- + ν̅e decays. The summed kinetic energy (Ee+e−) from such events is reconstructed and used to set limits, as a function of the χ mass, on the branching fraction for this decay channel.
© The Authors, published by EDP Sciences, 2019
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