CoreLumen Observational Series II : Full-Likelihood Validation with BOSS DR12

This record documents the second entry in the CoreLumen Observational Series (COS).

COS II performs a full-likelihood validation of the late-time growth deformation
indication previously identified in COS I. The analysis uses the BOSS DR12
consensus BAO+RSD dataset, including the full 9×9 covariance matrix across
three effective redshift bins.

A minimal phenomenological modification confined to the linear growth sector
is tested using a single deformation parameter p1 that modifies the effective
growth kernel through μ(a) = 1 + p1(1 − a).

The likelihood structure is evaluated through one-dimensional likelihood scans,
two-dimensional degeneracy contours, residual diagnostics, and profile
likelihood calculations over σ8.

The results show that the apparent growth deformation signal suggested by
compressed analyses is largely driven by a degeneracy between the deformation
parameter p1 and the matter fluctuation amplitude σ8. When σ8 is profiled,
the statistical preference for a non-zero deformation parameter becomes mild.

This Zenodo record provides a fully reproducible archive of the COS II
analysis pipeline, including the likelihood implementation, numerical
methods, data inputs, and figure outputs used in the manuscript.

COS II serves as a validation step in the CoreLumen Observational Series,
documenting the degeneracy structure of the DR12 dataset and establishing
a reproducible baseline for subsequent analyses using DESI-era data
and multi-probe observational combinations.