Ortho-Para Transition Rate in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>μ</mml:mi></mml:math>-Molecular Hydrogen and the Proton’s Induced Pseudoscalar Coupling<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>g</mml:mi><mml:mi>p</mml:mi></mml:msub></mml:math>
Bibliographic record
Abstract
We report a measurement of the ortho-para transition rate in the $p\ensuremath{\mu}p$ molecule. The experiment was conducted at TRIUMF via the measurement of the time dependence of the 5.2 MeV neutrons from muon capture in liquid hydrogen. The measurement yielded an ortho-para rate ${\ensuremath{\Lambda}}_{\mathrm{op}}=(11.1\ifmmode\pm\else\textpm\fi{}1.7\ifmmode\pm\else\textpm\fi{}\genfrac{}{}{0}{}{0.9}{0.6})\ifmmode\times\else\texttimes\fi{}{10}^{4}\text{ }\text{ }{\mathrm{s}}^{\ensuremath{-}1}$, which is substantially larger than the earlier result of Bardin et al. The result has striking implications for the proton's induced pseudoscalar coupling ${g}_{p}$, changing the value of ${g}_{p}$ obtained from the most precise ordinary muon capture measurement from $10.6\ifmmode\pm\else\textpm\fi{}2.7$ to $0.8\ifmmode\pm\else\textpm\fi{}2.8$, and from the sole radiative muon capture measurement from $12.2\ifmmode\pm\else\textpm\fi{}1.1$ to $10.6\ifmmode\pm\else\textpm\fi{}1.2$, bringing the latter result closer to theoretical predictions.
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.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.055 | 0.005 |
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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".