Observable detail · COS
DESI Year-3 BAO (forward)
| Prediction / mechanism | Homogeneous \(P(t)\) cancels from radial photon \(\chi(z)\); standard BAO comoving rulers are not shifted by the retired \(D_M/\sqrt{P_0}\) map. Forward: DESI Y3 will tighten \(D_M/r_d\) alongside the main BAO page. |
|---|---|
| Measured | DESI Year-1 12-bin \(D_M(z)/r_d\) (DESI Collab 2024); DESI Year-3 release expected 2026. |
| Residual / status | Legacy script branch \(\Delta\chi^2 \approx +33.6\) retained for audit reproducibility only — not a homogeneous prediction (dct_desi_bao_test.py header). |
| Status | neutral (homogeneous background; see bao) |
| Source paper | DCT-BAO-01 |
Mechanism
The May 2026 geometry revision documents null propagation under \(\tilde g_{\mu\nu} = P\,g_{\mu\nu}\): no uniform rescaling of photon comoving distances. DESI Y3 remains a sharp test of the expansion history and of any inhomogeneous or disformal extension of DCT; it does not revive the obsolete homogeneous-\(D_M\) map.
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 | Neutral at homogeneous background; see methodology note and /observables/bao/. |
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-full-shape · desi-w0-wa · m-lens-m-dyn.
Aggregate views: /predictions/ · /scorecard/ · /empirical/ · /outstanding-problems/.
Audit notes
This sub-page tracks the DESI Y3 forward window; substantive BAO geometry and scripts are shared with /observables/bao/ and DCT-BAO-01.
References
- DESI Collaboration 2024 (Year-1 BAO)
- Source paper: DCT-BAO-01
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