Observation of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>χ</mml:mi><mml:mrow><mml:mi>c</mml:mi><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo stretchy="false">(</mml:mo><mml:mn>2</mml:mn><mml:mi>P</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:math>meson in the reaction<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>γ</mml:mi><mml:mi>γ</mml:mi><mml:mo>→</mml:mo><mml:mi>D</mml:mi><mml:mover accent="true"><mml:mi>D</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:math>at<i>BABAR</i>
Bibliographic record
Abstract
A search for the $Z(3930)$ resonance in $\ensuremath{\gamma}\ensuremath{\gamma}$ production of the $D\overline{D}$ system has been performed using a data sample corresponding to an integrated luminosity of $384\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ recorded by the BABAR experiment at the PEP-II asymmetric-energy electron-positron collider. The $D\overline{D}$ invariant mass distribution shows clear evidence of the $Z(3930)$ state with a significance of $5.8\ensuremath{\sigma}$. We determine mass and width values of $(3926.7\ifmmode\pm\else\textpm\fi{}2.7\ifmmode\pm\else\textpm\fi{}1.1)\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ and $(21.3\ifmmode\pm\else\textpm\fi{}6.8\ifmmode\pm\else\textpm\fi{}3.6)\text{ }\text{ }\mathrm{MeV}$, respectively. A decay angular analysis provides evidence that the $Z(3930)$ is a tensor state with positive parity and $C$ parity (${J}^{PC}={2}^{++}$); therefore we identify the $Z(3930)$ state as the ${\ensuremath{\chi}}_{c2}(2P)$ meson. The value of the partial width ${\ensuremath{\Gamma}}_{\ensuremath{\gamma}\ensuremath{\gamma}}\ifmmode\times\else\texttimes\fi{}\mathcal{B}(Z(3930)\ensuremath{\rightarrow}D\overline{D})$ is found to be $(0.24\ifmmode\pm\else\textpm\fi{}0.05\ifmmode\pm\else\textpm\fi{}0.04)\text{ }\text{ }\mathrm{keV}$.
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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 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.003 | 0.006 |
| Insufficient payload (model declined to judge) | 0.090 | 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; 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".