Search for dark matter decay of the free neutron from the UCNA experiment: <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>n</mml:mi><mml:mo>→</mml:mo><mml:mi>χ</mml:mi><mml:mo>+</mml:mo><mml:msup><mml:mi>e</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>e</mml:mi><mml:mo>−</mml:mo></mml:msup></mml:mrow></mml:math>
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
It has been proposed recently that a previously unobserved neutron decay branch to a dark matter particle ($\ensuremath{\chi}$) 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 $\ensuremath{\chi}$ along with an ${e}^{+}{e}^{\ensuremath{-}}$ 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 $\ensuremath{\sim}4\ensuremath{\pi}$ acceptance using a pair of detectors that observe a volume of stored ultracold neutrons. The summed kinetic energy (${E}_{{e}^{+}{e}^{\ensuremath{-}}}$) from such events is used to set limits, as a function of the $\ensuremath{\chi}$ mass, on the branching fraction for this decay channel. For $\ensuremath{\chi}$ masses consistent with resolving the neutron lifetime discrepancy, we exclude this as the dominant dark matter decay channel at $\ensuremath{\gg}5\ensuremath{\sigma}$ level for $100<{E}_{{e}^{+}{e}^{\ensuremath{-}}}<644\phantom{\rule{4.pt}{0ex}}\text{keV}$. If the $\ensuremath{\chi}+{e}^{+}{e}^{\ensuremath{-}}$ final state is not the only one, we set limits on its branching fraction of $<{10}^{\ensuremath{-}4}$ for the above ${E}_{{e}^{+}{e}^{\ensuremath{-}}}$ range at $>90%$ confidence level.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.005 | 0.002 |
| Meta-epidemiology (narrow) | 0.003 | 0.005 |
| Meta-epidemiology (broad) | 0.002 | 0.007 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.005 | 0.006 |
| Scholarly communication | 0.004 | 0.003 |
| Open science | 0.009 | 0.008 |
| Research integrity | 0.004 | 0.006 |
| Insufficient payload (model declined to judge) | 0.092 | 0.009 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it