PROBING FUNDAMENTAL CONSTANT EVOLUTION WITH NEUTRAL ATOMIC GAS LINES
Bibliographic record
Abstract
We have detected narrow H i 21 cm and C i absorption at z ∼ 1.4–1.6 toward Q0458−020 and Q2337−011, and use these lines to test for possible changes in the fine structure constant α, the proton–electron mass ratio μ, and the proton gyromagnetic ratio g p . A comparison between the H i 21 cm and C i line redshifts yields Δ X / X = (+6.8 ± 1.0) × 10 −6 over 0 < 〈 z 〉 < 1.46, where X = g p α 2 /μ, and the errors are purely statistical, from the Gaussian fits. The simple line profiles and the high sensitivity of the spectra imply that statistical errors in this comparison are an order of magnitude lower than in previous studies. Further, the C i lines arise in cold neutral gas that also gives rise to H i 21 cm absorption, and both background quasars are core-dominated, reducing the likelihood of systematic errors due to local velocity offsets between the hyperfine and resonance lines. The dominant source of systematic error lies in the absolute wavelength calibration of the optical spectra, which appears uncertain to ∼2 km s −1 , yielding a maximum error in Δ X / X of ∼6.7 × 10 −6 . Including this, we obtain Δ X / X = (+6.8 ± 1.0(statistical) ± 6.7(max. systematic)) × 10 −6 over 0 < 〈 z 〉 < 1.46. Using literature constraints on Δμ/μ, this is inconsistent with claims of a smaller value of α from the many-multiplet method, unless fractional changes in g p are larger than those in α and μ.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".