Search For Invisible Nucleon Decay in SNO+ With Improved Sensitivity
Bibliographic record
Abstract
The water phase of the SNO+ (Sudbury Neutrino Observatory) experiment has completed after the collection of ~305 days of total livetime worth of data, divided into two main sets. The effective concentration of U-238 and Th-232 in the water was determined using in situ analysis to be, for the second set of data, gU/gH2O: (3.64 +/- 0.74_(stat) + 1.28_(syst) - 0.99_(syst) x 10^-15 and gTh/gH2O: (3.08 +/- 3.22_(stat) + 1.60_(syst) - 5.00_(syst) ) x 10^-16. The water data can also been used to search for ``invisible" modes of nucleon decay, and a previous SNO+ publication set world-leading limits on relevant nucleon and dinucleon decay modes except neutron and dineutron decay. This thesis presents a re-analysis of the ``invisible" neutron decay mode of that first set of data, which reoptimizes the fiducial volume and develops an improved treatment of the dominant energy systematic uncertainties. This leads to a world-leading lower limit on the ``invisible" neutron decay lifetime of 6.91 x 10^29 years. A sensitivity analysis shows that including the second set of data that has lower backgrounds is expected to yield a lower limit on the neutron decay lifetime of 1.57 x 10^30 years, further improving the result.
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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 | 0.005 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
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".