Where the Missing Neutrons Could Go
Source and asset notice, retrieved 2026-09-22.

claimant-summary.json is an attributed factual transcription from Bartosz
Fornal and Benjamin Grinstein, Dark Matter Interpretation of the Neutron Decay
Anomaly, Physical Review Letters 120, 191801 (2018), DOI
10.1103/PhysRevLett.120.191801. Numerical version arXiv:1801.01124v3.
The publisher identifies the published article as CC BY 4.0:
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.120.191801
https://creativecommons.org/licenses/by/4.0/
The extraction selects prose numbers, Equation (1) and the approximately 99%
proton-producing branch printed after it, converts them into
named JSON fields and adds explicit units, locations and page tolerances.
No third-party figure is used. The versioned arXiv PDF carries a separate
arXiv non-exclusive distribution licence; that PDF is not redistributed.

ucna-published-bound.json is an independent transcription of numerical facts
and their scope from X. Sun et al. (UCNA Collaboration), Search for dark matter
decay of the free neutron from the UCNA experiment: n to chi + e+e-,
Physical Review C 97, 052501(R) (2018), DOI 10.1103/PhysRevC.97.052501;
arXiv:1803.10890v1. Article copyright 2018 American Physical Society.
https://journals.aps.org/prc/abstract/10.1103/PhysRevC.97.052501
https://arxiv.org/licenses/nonexclusive-distrib/1.0/license.html
The two simulated signal energies (322 and 644 keV) are transcribed from the
Figure 4 legend; the figure itself is not reproduced.
No article, figure, spectrum or raw experimental record is redistributed.
This notice grants no reuse rights in the source article.

pdg-info.json, pdg-summary.json and pdg-listing.json are unchanged API
response bytes from the Particle Data Group's 2026 edition, neutron mean-life
listing S017T. F. Takahashi et al. (Particle Data Group), Review of Particle
Physics, International Journal of Modern Physics A 41, 2630011 (2026).
These three responses are used under CC BY 4.0, independently checked at:
https://pdgapi.lbl.gov/doc/restapi.html
https://pdgapi.lbl.gov/info
https://creativecommons.org/licenses/by/4.0/
Response selection is this page's; values, footnotes and timestamps are intact.

context-facts.json contains this page's factual notes and citations for:
Z. Tang et al., PRL 121, 022505 (2018), DOI 10.1103/PhysRevLett.121.022505,
APS accepted manuscript (not the earlier arXiv procedure);
M. Klopf et al., PRL 122, 222503 (2019), DOI 10.1103/PhysRevLett.122.222503,
arXiv:1905.01912v2;
B. Fornal and B. Grinstein, Neutron's Dark Secret, MPLA 35, 2030019 (2020),
DOI 10.1142/S0217732320300190, arXiv:2007.13931v1;
B. Fornal, Neutron Dark Decay, Universe 9, 449 (2023),
DOI 10.3390/universe9100449, arXiv:2306.11349v1;
B. Fornal and B. Grinstein, PRL erratum 124, 219901(E) (2020),
DOI 10.1103/PhysRevLett.124.219901 (publisher CC BY 4.0);
M. Vikiaris et al., PRD 114, 043032 (2026), DOI 10.1103/21p6-sqfh
(publisher abstract and bibliographic record only);
Y. Fuwa et al., Improved measurements of neutron lifetime with cold neutron
beam at J-PARC, arXiv:2412.19519v1 (abstract values transcribed);
A. M. Desai, Pressure-dependent detector effects in beam-based neutron
lifetime measurements, Eur. Phys. J. A 62, 154 (2026),
DOI 10.1140/epja/s10050-026-01929-x (abstract paraphrased only).
These facts are independently annotated. Full articles and figures are not
included, and this page does not assign an open licence to those source works.
Exact URLs and locations appear in context-facts.json and the page bibliography.

ucna-published-bound.json also carries the ceiling in the form the abstract
prints it ("< 10^-4"), so the engine can check the number against it.

beta-relation.json is an attributed factual transcription from Andrzej
Czarnecki, William J. Marciano and Alberto Sirlin, Neutron Lifetime and Axial
Coupling Connection, Physical Review Letters 120, 202002 (2018), DOI
10.1103/PhysRevLett.120.202002, arXiv:1802.01804v3; and from D. Dubbers,
H. Saul, B. Maerkisch, T. Soldner and H. Abele, Exotic decay channels are not
the cause of the neutron lifetime anomaly, Physics Letters B 791, 6-10 (2019),
DOI 10.1016/j.physletb.2019.02.013, arXiv:1812.00626v3. Both articles are
CC BY 4.0 according to their Crossref records:
https://creativecommons.org/licenses/by/4.0/
It also records one sentence of the claimants' reply from B. Fornal, Neutron
Dark Decay, Universe 9, 449 (2023), printed page 16, with its location, and
points to the PERKEO III (PRL 122, 242501 (2019)) and aSPECT (PRC 101, 055506
(2020)) measurements, whose values are read from the PDG listing below.

pdg-lambda-summary.json and pdg-lambda-listing.json are unchanged API response
bytes from the Particle Data Group's 2026 edition, neutron listing S017AV
(lambda = g_A / g_V), used under CC BY 4.0 as for the other PDG responses:
https://pdgapi.lbl.gov/summaries/S017AV
https://pdgapi.lbl.gov/listings/S017AV

context-facts.json now also cites J. Caylor et al., Detection of molecular
hydrogen in a neutron beam lifetime experiment, Physical Review C 112, 065501
(2025), DOI 10.1103/nr3b-3dtl (abstract phrase quoted), and the National
Institute of Standards and Technology news item Spotlight: Electromagnetic
Proton Trap at the NIST Center for Neutron Research (NCNR), dated 28 January
2026 (one sentence quoted, attributed).

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