Search for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>2</mml:mn><mml:mi>ν</mml:mi><mml:mi>β</mml:mi><mml:mi>β</mml:mi></mml:mrow></mml:math>decay of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Xe</mml:mi><mml:mprescripts/><mml:none/><mml:mn>136</mml:mn></mml:mmultiscripts></mml:math>to the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mn>0</mml:mn><mml:mn>1</mml:mn><mml:mo>+</mml:mo></mml:msubsup></mml:math>excited state of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Ba</mml:mi><mml:mprescripts/><mml:none/><mml:mn>136</mml:mn></mml:mmultiscripts></mml:math>with the EXO-200 liquid xenon detector
Bibliographic record
Abstract
EXO-200 is a single phase liquid xenon detector designed to search for neutrinoless $\ensuremath{\beta}\ensuremath{\beta}$ decay of $^{136}\mathrm{Xe}$ to the ground state of $^{136}\mathrm{Ba}$. We report here on a search for the two-neutrino $\ensuremath{\beta}\ensuremath{\beta}$ decay of $^{136}\mathrm{Xe}$ to the first ${0}^{+}$ excited state, ${0}_{1}^{+}$, of $^{136}\mathrm{Ba}$ based on a $100 \mathrm{kg}\phantom{\rule{0.16em}{0ex}}\mathrm{yr}$ exposure of $^{136}\mathrm{Xe}$. Using a specialized analysis employing a machine learning algorithm, we obtain a 90% CL half-life sensitivity of $1.7\ifmmode\times\else\texttimes\fi{}{10}^{24}$ yr. We find no statistically significant evidence for the $2\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ decay to the excited state resulting in a lower limit of ${T}_{1/2}^{2\ensuremath{\nu}} ({0}^{+}\ensuremath{\rightarrow}{0}_{1}^{+}) > 6.9 \ifmmode\times\else\texttimes\fi{}{10}^{23}$ yr at 90% CL. This observed limit is consistent with the estimated half-life of $2.5\ifmmode\times\else\texttimes\fi{}{10}^{25}$ yr.
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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 | 0.012 | 0.006 |
| Meta-epidemiology (narrow) | 0.007 | 0.011 |
| Meta-epidemiology (broad) | 0.003 | 0.013 |
| Bibliometrics | 0.003 | 0.008 |
| Science and technology studies | 0.010 | 0.011 |
| Scholarly communication | 0.008 | 0.009 |
| Open science | 0.016 | 0.014 |
| Research integrity | 0.009 | 0.012 |
| Insufficient payload (model declined to judge) | 0.059 | 0.016 |
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".