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Bibliographic record
Abstract
We present a combined measurement of the Cabibbo-Kobayashi-Maskawa matrix element $|{V}_{cb}|$ and of the parameters ${\ensuremath{\rho}}^{2}$, ${R}_{1}(1)$, and ${R}_{2}(1)$, which fully characterize the form factors for the ${B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}}$ decay in the framework of heavy-quark effective field theory. The results, based on a selected sample of about 52 800 ${B}^{0}\ensuremath{\rightarrow}{D}^{*\ensuremath{-}}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}}$ decays, recorded by the BABAR detector, are ${\ensuremath{\rho}}^{2}=1.157\ifmmode\pm\else\textpm\fi{}0.094\ifmmode\pm\else\textpm\fi{}0.027$, ${R}_{1}(1)=1.327\ifmmode\pm\else\textpm\fi{}0.131\ifmmode\pm\else\textpm\fi{}0.043$, ${R}_{2}(1)=0.859\ifmmode\pm\else\textpm\fi{}0.077\ifmmode\pm\else\textpm\fi{}0.021$, and $\mathcal{F}(1)|{V}_{cb}|=(34.7\ifmmode\pm\else\textpm\fi{}0.4\ifmmode\pm\else\textpm\fi{}1.0)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$. The first error is the statistical and the second is the systematic uncertainty. Combining these measurements with the previous BABAR measurement of the form factors, which employs a different fit technique on a partial sample of the data, we improve the statistical precision of the result, ${\ensuremath{\rho}}^{2}=1.191\ifmmode\pm\else\textpm\fi{}0.048\ifmmode\pm\else\textpm\fi{}0.028$, ${R}_{1}(1)=1.429\ifmmode\pm\else\textpm\fi{}0.061\ifmmode\pm\else\textpm\fi{}0.044$, ${R}_{2}(1)=0.827\ifmmode\pm\else\textpm\fi{}0.038\ifmmode\pm\else\textpm\fi{}0.022$, and $\mathcal{F}(1)|{V}_{cb}|=(34.4\ifmmode\pm\else\textpm\fi{}0.3\ifmmode\pm\else\textpm\fi{}1.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$. Using lattice calculations for the axial form factor $\mathcal{F}(1)$, we extract $|{V}_{cb}|=(37.4\ifmmode\pm\else\textpm\fi{}0.3\ifmmode\pm\else\textpm\fi{}1.2{\ifmmode\pm\else\textpm\fi{}}_{1.4}^{1.2})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, where the third error is due to the uncertainty in $\mathcal{F}(1)$. We also present a measurement of the exclusive branching fraction, $\mathcal{B}=(4.69\ifmmode\pm\else\textpm\fi{}0.04\ifmmode\pm\else\textpm\fi{}0.34)%$.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.005 |
| Meta-epidemiology (narrow) | 0.003 | 0.005 |
| Meta-epidemiology (broad) | 0.002 | 0.006 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.006 | 0.007 |
| Scholarly communication | 0.003 | 0.003 |
| Open science | 0.005 | 0.005 |
| Research integrity | 0.005 | 0.005 |
| Insufficient payload (model declined to judge) | 0.032 | 0.002 |
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; both teacher heads agree on what is shown here.
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".