Preserve CCL neutrino masses and species in CAMB predictions - #97
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CAMB previously defaulted to one 0.06-eV neutrino regardless of the CCL cosmology, so sigma8-to-As normalization and lensing spectra used the wrong background. Transfer the mass sum and resolved species, temperature and density as CCL does in its CAMB interface, and remove the redundant neutrino subtraction from CDM. Also preserve Neff, CMB temperature and curvature, and apply dark energy before normalization. Test massless, scalar and per-species inputs and the CCL/CAMB lensing mass response.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_0133mw5vATUB7QfqbhYac7Fz
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CAMB silently used its default 0.06-eV neutrino instead of the CCL mass, including during σ₈→Aₛ normalization.
The bridge now transfers the summed mass and resolved species, densities and temperatures, matching CCL's CAMB interface rather than approximating its hierarchy.
It also preserves Neff, T_CMB and Omega_k, applies w/wa before normalization, and removes the redundant neutrino subtraction from cold dark matter.
CAMB/CCL − 1 at ℓ=1000 (Planck defaults at fixed σ₈; Gaussian n(z), mean 0.7, width 0.2; CAMB 2.0.4 / CCL 3.3.6):
The two backends' mass responses agree within 1.3% at ℓ=100, 500 and 1000; their different nonlinear models remain unchanged.
All 50 tests in
test_camb_neutrinos.py,test_cosmology.pyandtest_cosmo.pypass in the Slurm/container environment.Tests cover zero mass, scalar/array inputs, normal/inverted/equal splits, background parameters and σ₈ normalization.
Default sp_validation iNKA predictions also change slightly because the bridge now preserves CCL's normal-hierarchy species (about +0.09% in this C₁₀₀₀).
Closes #96
— Sol on behalf of Cail
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