Siamese Universes V — EFT Embeddings and DESI Constraints on Holographic Twin Cosmologies

We embed the Siamese Universes CPT-symmetric cosmology into an effective field-theory framework.
A multiplicative suppression ansatz applied to the CLASS linear matter power spectrum reduces the Hubble tension (~2 σ), decreases σ₈ by ~3 %, and improves a light RSD χ² by +4.8 (~2.2 σ over ΛCDM).
The model is fully reproducible via included Python scripts and is falsifiable with Euclid and CMB-S4.