Observation of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>e</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>e</mml:mi><mml:mo>−</mml:mo></mml:msup><mml:mo>→</mml:mo><mml:msup><mml:mi>ρ</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>ρ</mml:mi><mml:mo>−</mml:mo></mml:msup></mml:math>near<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>10.58</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>GeV</mml:mi></mml:math>
Bibliographic record
Abstract
We report the first observation of ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{+}{\ensuremath{\rho}}^{\ensuremath{-}}$, in a data sample of $379\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected with the BABAR detector at the PEP-II ${e}^{+}{e}^{\ensuremath{-}}$ storage ring at center-of-mass energies near $\sqrt{s}=10.58\text{ }\text{ }\mathrm{GeV}$. We measure a cross section of $\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\rho}}^{+}{\ensuremath{\rho}}^{\ensuremath{-}})=8.3\ifmmode\pm\else\textpm\fi{}0.7(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.8(\mathrm{syst})\text{ }\text{ }\mathrm{fb}$ within the range of $|\mathrm{cos}{\ensuremath{\theta}}^{*}|<0.8$ and $|\mathrm{cos}{\ensuremath{\theta}}_{\ifmmode\pm\else\textpm\fi{}}|<0.85$, where ${\ensuremath{\theta}}^{*}$ is the center-of-mass polar angle of the ${\ensuremath{\rho}}^{\ifmmode\pm\else\textpm\fi{}}$ meson and ${\ensuremath{\theta}}_{\ifmmode\pm\else\textpm\fi{}}$ are the angles in the ${\ensuremath{\rho}}^{\ifmmode\pm\else\textpm\fi{}}$ rest frame between the direction of the boost from the laboratory frame and the direction of the ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$. Assuming production through single-photon annihilation, there are three independent helicity amplitudes. We measure the ratios of their squared moduli to be $|{F}_{00}{|}^{2}\ensuremath{\mathbin:}|{F}_{10}{|}^{2}\ensuremath{\mathbin:}|{F}_{11}{|}^{2}=\phantom{\rule{0ex}{0ex}}0.51\ifmmode\pm\else\textpm\fi{}0.14(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.07(\mathrm{syst})\ensuremath{\mathbin:}0.10\ifmmode\pm\else\textpm\fi{}0.04(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.01(\mathrm{syst})\ensuremath{\mathbin:}0.04\ifmmode\pm\else\textpm\fi{}0.03(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.01(\mathrm{syst})$. The $|{F}_{00}{|}^{2}$ result is inconsistent with the prediction of 1.0 made by QCD models with a significance of 3.1 standard deviations including systematic uncertainties.
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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 | 0.007 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.006 | 0.008 |
| Open science | 0.002 | 0.004 |
| Research integrity | 0.002 | 0.005 |
| Insufficient payload (model declined to judge) | 0.409 | 0.346 |
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".