Evaluation of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>E</mml:mi><mml:mn>2</mml:mn><mml:mo>/</mml:mo><mml:mi>M</mml:mi><mml:mn>1</mml:mn></mml:mrow></mml:math> ratio in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>N</mml:mi><mml:mo>→</mml:mo><mml:mi mathvariant="normal">Δ</mml:mi><mml:mo>(</mml:mo><mml:mn>1232</mml:mn><mml:mo>)</mml:mo></mml:mrow></mml:math> transition from the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi>γ</mml:mi><mml:mo></mml:mo></mml:mover><mml:mover accent="true"><mml:mi>p</mml:mi><mml:mo></mml:mo></mml:mover><mml:mo>→</mml:mo><mml:mi>p</mml:mi><mml:msup><mml:mi>π</mml:mi><mml:mn>0</mml:mn></mml:msup></mml:mrow></mml:math> reaction
Bibliographic record
Abstract
The transition from the nucleon to the $\mathrm{\ensuremath{\Delta}}(1232)$ resonance is a sensitive test for models of the nucleon structure. A magnetic dipole ($M1$) quark spin-flip transition essentially dominates photoexcitation of the $\mathrm{\ensuremath{\Delta}}$, but smaller components in the nucleon and $\mathrm{\ensuremath{\Delta}}$ wave functions allow also electric quadrupole ($E2$) contributions. The ratio $E2/M1$ then provides fundamental information on both the spatial deformation of the nucleon or $\mathrm{\ensuremath{\Delta}}$, and on the corresponding $D$ states in their quark-model wave functions. The authors measured the $E2/M1$ ratio via single ${\ensuremath{\pi}}^{0}$ production from the proton with a circularly polarized photon beam and a longitudinally polarized proton target, exploiting the presence of interference terms between the measured amplitudes that enhance the effect of smaller contributions. This most precise experimental result to date for the $E2/M1$ ratio gives deep insight into the nucleon properties and provides a precision benchmark for all nonperturbative QCD models.
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How this classification was reachedexpand
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 | 0.013 | 0.008 |
| Meta-epidemiology (narrow) | 0.006 | 0.011 |
| Meta-epidemiology (broad) | 0.003 | 0.013 |
| Bibliometrics | 0.003 | 0.008 |
| Science and technology studies | 0.010 | 0.009 |
| Scholarly communication | 0.010 | 0.010 |
| Open science | 0.013 | 0.010 |
| Research integrity | 0.011 | 0.012 |
| Insufficient payload (model declined to judge) | 0.249 | 0.014 |
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; both teacher heads agree on what is shown here.
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".