Observation of the Decay<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>B</mml:mi><mml:mo>→</mml:mo><mml:mi>J</mml:mi><mml:mo>/</mml:mo><mml:mi>ψ</mml:mi><mml:mi>η</mml:mi><mml:mi>K</mml:mi></mml:math>and Search for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>X</mml:mi><mml:mo>(</mml:mo><mml:mn>3872</mml:mn><mml:mo>)</mml:mo><mml:mo>→</mml:mo><mml:mi>J</mml:mi><mml:mo>/</mml:mo><mml:mi>ψ</mml:mi><mml:mi>η</mml:mi></mml:math>
Bibliographic record
Abstract
We report the observation of the $B$ meson decay ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\eta}{K}^{\ifmmode\pm\else\textpm\fi{}}$ and evidence for the decay ${B}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\eta}{K}_{\mathrm{S}}^{0}$, using $90\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ events collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the BABAR detector at the SLAC PEP-II ${e}^{+}{e}^{\ensuremath{-}}$ asymmetric-energy storage ring. We obtain branching fractions of $\mathcal{B}({B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\eta}{K}^{\ifmmode\pm\else\textpm\fi{}})=[10.8\ifmmode\pm\else\textpm\fi{}2.3(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t})\ifmmode\pm\else\textpm\fi{}2.4(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ and $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\eta}{K}_{\mathrm{S}}^{0})=[8.4\ifmmode\pm\else\textpm\fi{}2.6(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t})\ifmmode\pm\else\textpm\fi{}2.7(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$. We search for the new narrow mass state, the $X(3872)$, recently reported by the Belle Collaboration, in the decay ${B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}X(3872){K}^{\ifmmode\pm\else\textpm\fi{}},X(3872)\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\eta}$ and determine an upper limit of $\mathcal{B}[{B}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}X(3872){K}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\eta}{K}^{\ifmmode\pm\else\textpm\fi{}}]<7.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ at 90% confidence level.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.090 | 0.027 |
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".