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

doi:10.1103/PhysRevC.97.052501

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

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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 language	English
Article number	052501
Journal	Physical Review C
Volume	97
Issue number	5
DOIs	https://doi.org/10.1103/PhysRevC.97.052501
State	Published - May 21 2018

Bibliographical note

Publisher Copyright:
© 2018 American Physical Society.

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.

Funders	Funder number
National Science Foundation Arctic Social Science Program	NSF-1005233, NSF-1307426, NSF-1506459, 1812340, NSF-1205977, 1002814, 1506459, NSF-1002814, NSF-1615153, 1205977, NSF-1102511, 1005233, 1306997, 1307426, NSF-1306997
U.S. Department of Energy EPSCoR
Institute for Nuclear Physics	DE-FG02-08ER41557, DE-FG02-97ER41042, DE-SC0014622
Laboratory Directed Research and Development	20110043DR
Los Alamos National Laboratory

ASJC Scopus subject areas

Nuclear and High Energy Physics

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10.1103/PhysRevC.97.052501

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@article{fe922bd1d1f24fa9868715d1aa22fc7e,

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

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.",

author = "X. Sun and E. Adamek and B. Allgeier and M. Blatnik and Bowles, {T. J.} and Broussard, {L. J.} and Brown, {M. A.P.} and R. Carr and S. Clayton and C. Cude-Woods and S. Currie and Dees, {E. B.} and X. Ding and Filippone, {B. W.} and A. Garc{\'i}a and P. Geltenbort and S. Hasan and Hickerson, {K. P.} and J. Hoagland and R. Hong and Hogan, {G. E.} and Holley, {A. T.} and Ito, {T. M.} and A. Knecht and Liu, {C. Y.} and J. Liu and M. Makela and R. Mammei and Martin, {J. W.} and D. Melconian and Mendenhall, {M. P.} and Moore, {S. D.} and Morris, {C. L.} and S. Nepal and N. Nouri and Pattie, {R. W.} and {P{\'e}rez Galv{\'a}n}, A. and Phillips, {D. G.} and R. Picker and Pitt, {M. L.} and B. Plaster and Ramsey, {J. C.} and R. Rios and Salvat, {D. J.} and A. Saunders and W. Sondheim and S. Sjue and S. Slutsky and C. Swank and G. Swift",

note = "Publisher Copyright: {\textcopyright} 2018 American Physical Society.",

year = "2018",

month = may,

day = "21",

doi = "10.1103/PhysRevC.97.052501",

language = "English",

volume = "97",

number = "5",

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T1 - Search for dark matter decay of the free neutron from the UCNA experiment

T2 - N→χ+e+e-

AU - Sun, X.

AU - Adamek, E.

AU - Allgeier, B.

AU - Blatnik, M.

AU - Bowles, T. J.

AU - Broussard, L. J.

AU - Brown, M. A.P.

AU - Carr, R.

AU - Clayton, S.

AU - Cude-Woods, C.

AU - Currie, S.

AU - Dees, E. B.

AU - Ding, X.

AU - Filippone, B. W.

AU - García, A.

AU - Geltenbort, P.

AU - Hasan, S.

AU - Hickerson, K. P.

AU - Hoagland, J.

AU - Hong, R.

AU - Hogan, G. E.

AU - Holley, A. T.

AU - Ito, T. M.

AU - Knecht, A.

AU - Liu, C. Y.

AU - Liu, J.

AU - Makela, M.

AU - Mammei, R.

AU - Martin, J. W.

AU - Melconian, D.

AU - Mendenhall, M. P.

AU - Moore, S. D.

AU - Morris, C. L.

AU - Nepal, S.

AU - Nouri, N.

AU - Pattie, R. W.

AU - Pérez Galván, A.

AU - Phillips, D. G.

AU - Picker, R.

AU - Pitt, M. L.

AU - Plaster, B.

AU - Ramsey, J. C.

AU - Rios, R.

AU - Salvat, D. J.

AU - Saunders, A.

AU - Sondheim, W.

AU - Sjue, S.

AU - Slutsky, S.

AU - Swank, C.

AU - Swift, G.

PY - 2018/5/21

Y1 - 2018/5/21

N2 - 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.

AB - 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.

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DO - 10.1103/PhysRevC.97.052501

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VL - 97

JO - Physical Review C

JF - Physical Review C

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ER -

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

Abstract

Bibliographical note

Funding

ASJC Scopus subject areas

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