An analysis of constraints on relativistic species from primordial\n nucleosynthesis and the cosmic microwave background
Bibliographic record
Abstract
We present constraints on the number of relativistic species from a joint\nanalysis of cosmic microwave background (CMB) fluctuations and light element\nabundances (helium and deuterium) compared to big bang nucleosynthesis (BBN)\npredictions. Our BBN calculations include updates of nuclear rates in light of\nrecent experimental and theoretical information, with the most significant\nchange occuring for the d(p,gamma)^3He cross section. We calculate a likelihood\nfunction for BBN theory and observations that accounts for both observational\nerrors and nuclear rate uncertainties and can be easily embedded in\ncosmological parameter fitting. We then demonstrate that CMB and BBN are in\ngood agreement, suggesting that the number of relativistic species did not\nchange between the time of BBN and the time of recombination. The level of\nagreement between BBN and CMB, as well as the agreement with the standard model\nof particle physics, depends somewhat on systematic differences among\ndeterminations of the primordial helium abundance. We demonstrate that\ninteresting constraints can be derived combining only CMB and D/H observations\nwith BBN theory, suggesting that an improved D/H constraint would be an\nextremely valuable probe of cosmology.\n
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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 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 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".