Observable detail · COS
Sound horizon \(r_d\) at drag
| Prediction / mechanism | \(r_d \approx 147.18\) Mpc inherited at recombination (\(P \to 1\)). Any legacy large BAO \(\Delta\chi^2\) tracked a retracted late-time \(D_M\) rescaling (obsolete vs photon null \(\chi\)); it does not indict \(r_d\). See /observables/bao/. |
|---|---|
| Measured | Planck 2018 PR3 \(r_d = 147.21 \pm 0.23\) Mpc. |
| Residual / status | HIT — inherited at recombination |
| Status | HIT |
| Source paper | DCT-BAO-01 |
Mechanism
At recombination the coherence field is uncondensed (\(P \to 1\)) so \(r_d\) inherits the \(\Lambda\)CDM value.
Derivation
The derivation chain follows the cluster paper DCT-BAO-01 and reduces to the canonical DCT constants (\(P_0 = 0.851\), \(\omega_0 = 50{,}037\), \(c_{BD} = 138{,}189\), master identity \(2\omega_0 + 3 = c_{BD} \cdot P_0^2 = 100{,}077\)). See the cluster paper for the full multi-line derivation.
Methodology
| Domain | Cosmology (COS) |
|---|---|
| Input data source | See "References" below for the canonical public-archive citation. |
| Measurement procedure | The measured value used here is the most recent peer-reviewed central value plus 1σ uncertainty from the cited reference. |
| Acceptance threshold | HIT: residual within 1σ of measurement. SOFT: directional agreement 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 verdict pill above. |
Python verification
Verification script: dct_desi_bao_test.py. Run with python3 dct_desi_bao_test.py to reproduce the canonical DCT result against the public-archive measurement source listed below.
Cross-references
Related observables: bao · desi-y3-bao.
Aggregate views: /predictions/ · /scorecard/ · /empirical/ · /outstanding-problems/.
Audit notes
This sub-page is part of the post-build-out of the observable archive (see the observable index). Verdict reflects the corpus-canonical (constant-\(P_0\)) treatment. The cluster-paper deep-link above (DCT-BAO-01) is the canonical source of the derivation chain.
References
- Planck Collaboration 2020
- Source paper: DCT-BAO-01
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