Normal single-spin asymmetries in electron-proton scattering: Two-photon exchange with intermediate-state resonances
Bibliographic record
Abstract
We calculate the beam (${B}_{n}$) and target (${A}_{n}$) normal single-spin asymmetries in electron--proton elastic scattering from two-photon exchange amplitudes with resonance intermediate states of spin-parity $1/{2}^{\ifmmode\pm\else\textpm\fi{}}$ and $3/{2}^{\ifmmode\pm\else\textpm\fi{}}$ and mass $W\ensuremath{\lesssim}1.8$ GeV. The latest CLAS exclusive meson electroproduction data are used as input for the transition amplitudes from the proton to the excited resonance states. For ${B}_{n}$, the spin 3/2 resonances dominate by an order of magnitude over the spin 1/2 states. In general we observe cancellations between the negative contributions of the $\mathrm{\ensuremath{\Delta}}(1232)$ and $N(1520)$ across both beam energy and scattering angle, and the positive contributions of the $\mathrm{\ensuremath{\Delta}}(1700)$ and $N(1720)$, leading to a rather large overall uncertainty band in the total ${B}_{n}$. At forward angles and beam energies ${E}_{\text{lab}}<1$ GeV, where the $\mathrm{\ensuremath{\Delta}}(1232)$ dominates, the calculated ${B}_{n}$ tend to overshoot the A4 and SAMPLE data. The calculated ${B}_{n}$ compare well with the measured values from the A4 and ${Q}_{\text{weak}}$ experiments with ${E}_{\text{lab}}>1$ GeV.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".