Z3 Pre-Registration: Cross-Survey Ωm Baseline Unification Test (v0.2)

Status: v0.2 canonical at uha commit 839ce60. Deposit-ready. GATE:OPEN given by Eric 2026-05-04 17:42 UTC. This deposit pre-registers Track B of the three-track UHA + EB carrier program: the cross-survey Ωm baseline common-baseline audit. Track B asks whether different cosmological surveys use different Ωm derivation chains and baselines, whether those differences create systematic effects appearing as cosmological tensions, and whether applying a unified UHA-derived Ωm baseline reduces those tensions across surveys. Z3 is not a Hubble-tension solution paper. It is a pre-registered cross-survey common-baseline audit. Its success condition is not "H0 solved" — it is "a locked Ωm substitution reduces joint tension under identical likelihoods, without extra degrees of freedom, and robustly across local-calibrator routes." Z3 does not directly challenge the SH0ES distance-ladder calibration. It tests whether cross-survey Ωm baseline substitution changes the joint-inference tension after the local-ladder H0 measurement is held fixed as a public-data constraint. Hypotheses (Track B): H0-Z3: Surveys use Ωm baselines that agree within statistical uncertainty (|ΔΩ_m| < 0.005). Substituting a unified UHA-derived Ωm baseline produces no significant Δχ² improvement (Δχ² ≤ 5 per Z0 §1.4). H1-Z3: Surveys use Ωm baselines that differ systematically (|ΔΩ_m| ≥ 0.005). Substituting a unified UHA-derived Ωm baseline produces Δχ² ≥ 20 improvement under identical likelihoods and no degree-of-freedom inflation. Termination criteria K0-Z3 … K4-Z3 lock five preregistered halt conditions (KS aliases deprecated). A K-firing is a successful preregistered outcome — the test ran and falsified its mechanism cleanly. A clean null is a co-equal publishable outcome per Z0 §9. v0.2 delta from v0.1 (2026-05-01): Δχ² thresholds normalized to Z0 5/20/49 hierarchy throughout; KS labels deprecated and aliased to canonical K0-Z3 … K4-Z3; venue-prestige routing removed; κ pre-Phase-3 lock procedure inserted; cross-protocol cascade narrowed (Z3 null halts Track B only, not all UHA coordinate-provenance tests); EB three-outcome primitive table added; local-anchor and distance-ladder route stratification added (Cepheid / TRGB / JAGB, Madore-style); Pantheon+ SN-transfer separation added; "common-baseline audit" language used in decision rules; Bayes-factor narrowing (BF>3) for Track B adjudication; explicit non-challenge of SH0ES distance ladder; clean-null = valid publishable outcome surfaced. Full changelog in §11 of the manuscript. Public-data scope: SH0ES R22, Planck 2018, KiDS-1000, DES Y3, DESI DR1, Pantheon+. Dataset versions, release dates, and access dates recorded at analysis start. Provenance: Source protocol: Omega_M_Baseline_Unification_Experiment_Complete_v1.0_77b639c.md (commit 77b639c; patent gates removed 2026-05-01) Companion protocol: UHA_Coordinate_Framework_Experiment_Complete_v1.0_77b639c.md Z0 umbrella: DOI 10.5281/zenodo.19881689 (deposited 2026-04-29) Z2 audit framework: DOI 10.5281/zenodo.19908184 (deposited 2026-04-29) EB carrier theorem: RSOS-260797 r4 (under review) UHA patent: US 63/902,536 Bootstrap commit: 839ce60 in github.com/abba-01/uha This Z3 deposits the Ωm-baseline-unification hypothesis as one candidate explanation for cross-survey cosmological tensions. Other candidates remain open and are listed in §5.