Measurement of the branching fractions of $ \overline{B} $ → D$^{(*)}$K$^{−} {K}_{(S)}^{\left(\ast \right)0} $ and $ \overline{B} $ → D$^{(*)} {D}_s^{-} $ decays at Belle II
Bibliographic record
Abstract
We present measurements of the branching fractions of eight $ {\overline{B}}^0 $ → D$^{(*)+}$K$^{−} {K}_{(S)}^{\left(\ast \right)0} $, B$^{−}$ → D$^{(*)0}$K$^{−} {K}_{(S)}^{\left(\ast \right)0} $ decay channels. The results are based on data from SuperKEKB electron-positron collisions at the Υ(4S) resonance collected with the Belle II detector, corresponding to an integrated luminosity of 362 fb$^{−1}$. The event yields are extracted from fits to the distributions of the difference between expected and observed B meson energy, and are efficiency-corrected as a function of m(K$^{−} {K}_{(S)}^{\left(\ast \right)0} $) and m(D$^{(*)} {K}_{(S)}^{\left(\ast \right)0} $) in order to avoid dependence on the decay model. These results include the first observation of $ {\overline{B}}^0 $ → D$^{+}$K$^{−} {K}_S^0 $, B$^{−}$ → D*$^{0}$K$^{−} {K}_S^0 $, and $ {\overline{B}}^0 $ → D*$^{+}$K$^{−} {K}_S^0 $ decays and a significant improvement in the precision of the other channels compared to previous measurements. The helicity-angle distributions and the invariant mass distributions of the K$^{−} {K}_{(S)}^{\left(\ast \right)0} $ systems are compatible with quasi-two-body decays via a resonant transition with spin-parity J$^{P}$ = 1$^{−}$ for the K$^{−} {K}_S^0 $ systems and J$^{P}$ = 1$^{+}$ for the K$^{−}$K*$^{0}$ systems. We also present measurements of the branching fractions of four $ {\overline{B}}^0 $ → D$^{(*)+} {D}_s^{-} $, B$^{−}$ → D$^{(*)0} {D}_s^{-} $ decay channels with a precision compatible to the current world averages.[graphic not available: see fulltext]
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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 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".