Observation of a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover><mml:mi>K</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mrow><mml:mi>N</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:mrow></mml:math> bound state in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mi>He</mml:mi><mml:mprescripts/><mml:none/><mml:mn>3</mml:mn></mml:mmultiscripts><mml:mo>(</mml:mo><mml:msup><mml:mi>K</mml:mi><mml:mo>−</mml:mo></mml:msup><mml:mo>,</mml:mo><mml:mi mathvariant="normal">Λ</mml:mi><mml:mi>p</mml:mi><mml:mo>)</mml:mo><mml:mi>n</mml:mi></mml:mrow></mml:math> reaction
Bibliographic record
Abstract
We have performed an exclusive measurement of the ${K}^{\ensuremath{-}}+\phantom{\rule{0.16em}{0ex}}^{3}\mathrm{He}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}pn$ reaction at an incident kaon momentum of $1\phantom{\rule{4pt}{0ex}}\mathrm{GeV}/c$. In the $\mathrm{\ensuremath{\Lambda}}p$ invariant mass spectrum, a clear peak was observed below the mass threshold of $\overline{K}+N+N$, as a signal of the kaonic nuclear bound state, $\overline{K}NN$. The binding energy, decay width, and $S$-wave Gaussian reaction form factor of this state were observed to be ${B}_{K}=42\ifmmode\pm\else\textpm\fi{}3{(\mathrm{stat}.)}_{\ensuremath{-}4}^{+3}(\mathrm{syst}.)\phantom{\rule{4pt}{0ex}}\mathrm{MeV}, {\mathrm{\ensuremath{\Gamma}}}_{K}=100\ifmmode\pm\else\textpm\fi{}7{(\mathrm{stat}.)}_{\ensuremath{-}9}^{+19}(\mathrm{syst}.)\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$, and ${Q}_{K}=383\ifmmode\pm\else\textpm\fi{}11{(\mathrm{stat}.)}_{\ensuremath{-}1}^{+4}(\mathrm{syst}.)\phantom{\rule{4pt}{0ex}}\mathrm{MeV}/c$, respectively. The total production cross section of $\overline{K}NN$, determined by its $\mathrm{\ensuremath{\Lambda}}p$ decay mode, was ${\ensuremath{\sigma}}_{K}^{\mathrm{tot}}B{R}_{\mathrm{\ensuremath{\Lambda}}p}=9.3\ifmmode\pm\else\textpm\fi{}0.8{(\mathrm{stat}.)}_{\ensuremath{-}1.0}^{+1.4}(\mathrm{syst}.)\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{b}$. We estimated the branching ratio of the $\overline{K}NN$ state to the $\mathrm{\ensuremath{\Lambda}}p$ and ${\mathrm{\ensuremath{\Sigma}}}^{0}p$ decay modes as $B{R}_{\mathrm{\ensuremath{\Lambda}}p}/B{R}_{{\mathrm{\ensuremath{\Sigma}}}^{0}p}\ensuremath{\sim}1.7$, by assuming that the physical processes leading to the $\mathrm{\ensuremath{\Sigma}}NN$ final states are analogous to those of $\mathrm{\ensuremath{\Lambda}}pn$.
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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 | 0.005 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.003 | 0.002 |
| Scholarly communication | 0.004 | 0.007 |
| Open science | 0.002 | 0.004 |
| Research integrity | 0.002 | 0.005 |
| Insufficient payload (model declined to judge) | 0.118 | 0.035 |
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".