Study of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>η</mml:mi></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>η</mml:mi><mml:mo>′</mml:mo></mml:math> Photoproduction at MAMI
Bibliographic record
Abstract
The reactions $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\eta}p$ and $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\eta}}^{\ensuremath{'}}p$ are measured from their thresholds up to the center-of-mass energy $W=1.96\text{ }\text{ }\mathrm{GeV}$ with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross sections are obtained with unprecedented statistical accuracy, providing fine energy binning and full production-angle coverage. A strong cusp is observed in the total cross section for $\ensuremath{\eta}$ photoproduction at the energies in the vicinity of the ${\ensuremath{\eta}}^{\ensuremath{'}}$ threshold, $W=1896\text{ }\text{ }\mathrm{MeV}$ (${E}_{\ensuremath{\gamma}}=1447\text{ }\text{ }\mathrm{MeV}$). Within the framework of a revised $\ensuremath{\eta}\mathrm{MAID}$ isobar model, the cusp, in connection with a steep rise of the ${\ensuremath{\eta}}^{\ensuremath{'}}$ total cross section from its threshold, can only be explained by a strong coupling of the poorly known $N(1895)1/{2}^{\ensuremath{-}}$ state to both $\ensuremath{\eta}p$ and ${\ensuremath{\eta}}^{\ensuremath{'}}p$. Including the new high-accuracy results in the $\ensuremath{\eta}\mathrm{MAID}$ fit to available $\ensuremath{\eta}$ and ${\ensuremath{\eta}}^{\ensuremath{'}}$ photoproduction data allows the determination of the $N(1895)1/{2}^{\ensuremath{-}}$ properties.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.015 | 0.004 |
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".