Upper Limit on the Photoproduction Cross Section of the Spin-Exotic <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>π</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> </mml:msub> <mml:mo stretchy="false">(</mml:mo> <mml:mn>1600</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math>
Bibliographic record
Abstract
The spin-exotic hybrid meson ${\ensuremath{\pi}}_{1}(1600)$ is predicted to have a large decay rate to the $\ensuremath{\omega}\ensuremath{\pi}\ensuremath{\pi}$ final state. Using $76.6\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ of data collected with the GlueX detector, we measure the cross sections for the reactions $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\omega}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}p$, $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\omega}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}p$, and $\ensuremath{\gamma}p\ensuremath{\rightarrow}\ensuremath{\omega}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\mathrm{\ensuremath{\Delta}}}^{++}$ in the range ${E}_{\ensuremath{\gamma}}=8--10\text{ }\text{ }\mathrm{GeV}$. Using isospin conservation, we set the first upper limits on the photoproduction cross sections of the ${\ensuremath{\pi}}_{1}^{0}(1600)$ and ${\ensuremath{\pi}}_{1}^{\ensuremath{-}}(1600)$. We combine these limits with lattice calculations of decay widths and find that photoproduction of ${\ensuremath{\eta}}^{\ensuremath{'}}\ensuremath{\pi}$ is the most sensitive two-body system to search for the ${\ensuremath{\pi}}_{1}(1600)$.
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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 | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.031 | 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".