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Bibliographic record
Abstract
We report measurements of partial branching fractions for inclusive charmless semileptonic $B$ decays $\overline{B}\ensuremath{\rightarrow}{X}_{u}\ensuremath{\ell}\overline{\ensuremath{\nu}}$ and the determination of the Cabibbo--Kobayashi--Maskawa (CKM) matrix element $|{V}_{ub}|$. The analysis is based on a sample of $467\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $\ensuremath{\Upsilon}(4S)\ensuremath{\rightarrow}B\overline{B}$ decays recorded with the BABAR detector at the PEP-II ${e}^{+}{e}^{\ensuremath{-}}$ storage rings. We select events in which the decay of one of the $B$ mesons is fully reconstructed and an electron or a muon signals the semileptonic decay of the other $B$ meson. We measure partial branching fractions $\ensuremath{\Delta}\mathcal{B}$ in several restricted regions of phase space and determine the CKM element $|{V}_{ub}|$ based on different QCD predictions. For decays with a charged lepton momentum ${p}_{\ensuremath{\ell}}^{*}>1.0\text{ }\text{ }\mathrm{GeV}$ in the $B$ meson rest frame, we obtain $\ensuremath{\Delta}\mathcal{B}=(1.80\ifmmode\pm\else\textpm\fi{}{0.13}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}{0.15}_{\mathrm{sys}}\ifmmode\pm\else\textpm\fi{}{0.02}_{\mathrm{theo}})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ from a fit to the two-dimensional ${M}_{X}\ensuremath{-}{q}^{2}$ distribution. Here, ${M}_{X}$ refers to the invariant mass of the final state hadron $X$ and ${q}^{2}$ is the invariant mass squared of the charged lepton and neutrino. From this measurement we extract $|{V}_{ub}|=(4.33\ifmmode\pm\else\textpm\fi{}{0.24}_{\mathrm{exp}}\ifmmode\pm\else\textpm\fi{}{0.15}_{\mathrm{theo}})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ as the arithmetic average of four results obtained from four different QCD predictions of the partial rate. We separately determine partial branching fractions for ${\overline{B}}^{0}$ and ${B}^{\ensuremath{-}}$ decays and derive a limit on the isospin breaking in $\overline{B}\ensuremath{\rightarrow}{X}_{u}\ensuremath{\ell}\overline{\ensuremath{\nu}}$ decays.
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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 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.004 | 0.004 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.127 | 0.044 |
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".