Search for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>η</mml:mi><mml:mo>′</mml:mo></mml:msup></mml:math> Bound Nuclei in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">C</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>12</mml:mn></mml:mrow></mml:mmultiscripts><mml:mo stretchy="false">(</mml:mo><mml:mi>γ</mml:mi><mml:mo>,</mml:mo><mml:mi>p</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:math> Reaction with Simultaneous Detection of Decay Products
Bibliographic record
Abstract
We measured missing mass spectrum of the $^{12}\mathrm{C}(\ensuremath{\gamma},p)$ reaction for the first time in coincidence with potential decay products from ${\ensuremath{\eta}}^{\ensuremath{'}}$ bound nuclei. We tagged an ($\ensuremath{\eta}+p$) pair associated with the ${\ensuremath{\eta}}^{\ensuremath{'}}N\ensuremath{\rightarrow}\ensuremath{\eta}N$ process in a nucleus. After applying kinematical selections to reduce backgrounds, no signal events were observed in the bound-state region. An upper limit of the signal cross section in the opening angle $\mathrm{cos}{\ensuremath{\theta}}_{\mathrm{lab}}^{\ensuremath{\eta}p}<\ensuremath{-}0.9$ was obtained to be $2.2\text{ }\text{ }\mathrm{nb}/\mathrm{sr}$ at the 90% confidence level. It is compared with theoretical cross sections, whose normalization ambiguity is suppressed by measuring a quasifree ${\ensuremath{\eta}}^{\ensuremath{'}}$ production rate. Our results indicate a small branching fraction of the ${\ensuremath{\eta}}^{\ensuremath{'}}N\ensuremath{\rightarrow}\ensuremath{\eta}N$ process and/or a shallow ${\ensuremath{\eta}}^{\ensuremath{'}}$-nucleus potential.
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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 | 0.001 | 0.005 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.002 | 0.002 |
| Bibliometrics | 0.004 | 0.006 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.005 | 0.006 |
| Open science | 0.003 | 0.005 |
| Research integrity | 0.004 | 0.003 |
| Insufficient payload (model declined to judge) | 0.619 | 0.605 |
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".