DESI DR1 tracers and CPL parameters
Individual run · T-78dd8606e857
Public summary of an internal test, not yet independently validated or published.
Question investigated
In DESI DR1, do luminous red galaxies at effective z = 0.51 favor the point w₀ = −0.838 and wₐ = −0.62 over the cosmological constant?
Test conditions
Use the official DESI DR1 full-shape analysis for luminous red galaxies at effective z = 0.51. Compare the reference w₀ = −1, wₐ = 0 with the alternative w₀ = −0.838, wₐ = −0.62, fitting nuisance bias parameters and retaining the Planck angular constraint. Define Δχ² = reference χ² − alternative χ².
Result
Δχ² = 1.52: the alternative point has a lower χ², but the improvement falls short of the prespecified decision criteria. The result does not establish a preference for the alternative in this fixed-point comparison.
Key figure
Reference χ² − alternative χ²
1.52
w₀ = -0.838, wₐ = -0.62
Source: Tower public snapshot
Specific limitations
- The comparison involves two fixed points in parameter space. It does not explore the full parameter distribution or measure the global significance of an alternative to the cosmological constant.
- Δχ² = reference χ² − alternative χ². A positive value indicates a lower-χ² fit for the alternative. The comparison involves fixed cosmological points: Δχ² alone does not provide a significance in σ or a probability. The conclusion depends on the data and criteria used.