Observation of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>B</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:mo>→</mml:mo><mml:msup><mml:mover accent="true"><mml:mi>K</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mn>0</mml:mn></mml:msup><mml:msup><mml:mi>K</mml:mi><mml:mo>+</mml:mo></mml:msup></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>B</mml:mi><mml:mn>0</mml:mn></mml:msup><mml:mo>→</mml:mo><mml:msup><mml:mi>K</mml:mi><mml:mn>0</mml:mn></mml:msup><mml:msup><mml:mover accent="true"><mml:mi>K</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mn>0</mml:mn></mml:msup></mml:math>
Bibliographic record
Abstract
We report observations of the $b\ensuremath{\rightarrow}d$ penguin-dominated decays ${B}^{+}\ensuremath{\rightarrow}{\overline{K}}^{0}{K}^{+}$ and ${B}^{0}\ensuremath{\rightarrow}{K}^{0}{\overline{K}}^{0}$ in $316\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of ${e}^{+}{e}^{\ensuremath{-}}$ collision data collected with the BABAR detector. We measure the branching fractions $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{\overline{K}}^{0}{K}^{+})=(1.61\ifmmode\pm\else\textpm\fi{}0.44\ifmmode\pm\else\textpm\fi{}0.09)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ and $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{K}^{0}{\overline{K}}^{0})=(1.08\ifmmode\pm\else\textpm\fi{}0.28\ifmmode\pm\else\textpm\fi{}0.11)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ and the $CP$-violating charge asymmetry ${\mathcal{A}}_{CP}({\overline{K}}^{0}{K}^{+})=0.10\ifmmode\pm\else\textpm\fi{}0.26\ifmmode\pm\else\textpm\fi{}0.03$. Using a vertexing technique previously employed in several analyses of all-neutral final states containing kaons, we report the first measurement of time-dependent $CP$-violating asymmetries in ${B}^{0}\ensuremath{\rightarrow}{K}_{S}^{0}{K}_{S}^{0}$, obtaining $S=\ensuremath{-}{1.28}_{\ensuremath{-}0.73\ensuremath{-}0.16}^{+0.80+0.11}$ and $C=\ensuremath{-}0.40\ifmmode\pm\else\textpm\fi{}0.41\ifmmode\pm\else\textpm\fi{}0.06$. We also report improved measurements of the branching fraction $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{K}^{0}{\ensuremath{\pi}}^{+})=(23.9\ifmmode\pm\else\textpm\fi{}1.1\ifmmode\pm\else\textpm\fi{}1.0)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ and $CP$-violating charge asymmetry ${\mathcal{A}}_{CP}({K}^{0}{\ensuremath{\pi}}^{+})=\ensuremath{-}0.029\ifmmode\pm\else\textpm\fi{}0.039\ifmmode\pm\else\textpm\fi{}0.010$.
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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 | 0.007 |
| 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 | 0.005 | 0.008 |
| Open science | 0.003 | 0.004 |
| Research integrity | 0.002 | 0.004 |
| Insufficient payload (model declined to judge) | 0.382 | 0.318 |
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".