Observable detail · COSMOLOGY
Goldstone-θ ΔN_eff
| Prediction | +0.027 |
|---|---|
| Measured | Awaiting CMB-S4 (2030s) |
| Residual | open |
| Status | open |
| Source paper | DCT-CMB-01 |
Mechanism
ΔN_eff = (4/7)(g*_dec / g*_now)^(4/3) = (4/7)(10.75/106.75)^(4/3) = 0.0268. Goldstone θ-mode of the broken Z_3 symmetry contributes one relativistic species at decoupling, but with the temperature ratio set by the SM degrees-of-freedom evolution.
Derivation
ΔN_eff = (4/7)(g*_dec / g*_now)^(4/3) = (4/7)(10.75/106.75)^(4/3) = 0.0268. Goldstone θ-mode of the broken Z_3 symmetry contributes one relativistic species at decoupling, but with the temperature ratio set by the SM degrees-of-freedom evolution.
The closed-form prediction is
$$ \text{predicted} = +0.027 $$against the measurement Awaiting CMB-S4 (2030s), giving residual open.
Python verification
The verification script for this observable is cmb_analysis.py. Run it with python3 cmb_analysis.py to reproduce the canonical DCT result against the public-archive measurement source listed above (CMB-S4 baseline forecast σ(ΔN_eff) ≈ 0.03.).
Methodology
| Domain | Cosmology (COS) |
|---|---|
| Input data source | See "References" below for the canonical public-archive citation. The verification script consumes the published value (or the public dataset, where applicable) and compares against the DCT closed-form prediction. |
| Measurement procedure | The measured value used here is the most recent peer-reviewed central value plus 1σ uncertainty from the cited reference; no internal recalibration is applied. |
| Acceptance threshold | HIT: residual within 1σ of measurement. SOFT: directional agreement, residual within bracketing range. OPEN: untested or unresolved. |
| Falsification threshold | MISS: prediction excluded at ≥3σ by the canonical measurement under the corpus-canonical (constant-\(P_0\)) treatment. |
| Current status | See the verdict pill in the prediction table above. |
Cross-references
Related observables in the same domain: planck-cmb-tt · bbn-abundances.
Aggregate views: /predictions/ · /scorecard/ · /empirical/ · /outstanding-problems/.
Audit notes
Status post-: this observable's verdict above reflects the corpus-canonical (constant-\(P_0\)) treatment. Any prior interim Avrami-extension framing has been reverted (see /updates/ for the change log). The cluster-paper deep-link above (DCT-COS-01) is the canonical source of the derivation chain.
References
- CMB-S4 Collaboration
- Source paper: DCT-CMB-01
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