Identify the source of the separation among mock-catalog distributions

Identify whether the separation between the Abacus FFA, Abacus altMTL, and EZmock $chi^2$ distributions is caused specifically by the treatment of fiber assignment, by other differences in mock construction, or by the analytic covariance model.

Background

The analytic-covariance chi2chi^2 analysis produces different distributions for the mock ensembles. In particular, the Abacus altMTL distribution is shifted toward larger chi2chi^2 values relative to the Abacus FFA and EZmock distributions.

The paper notes that this separation could reflect differences in fiber-assignment treatments, other aspects of mock construction, or the covariance model itself, but does not resolve which explanation is responsible. Resolving this issue is important for assessing the reliability of mock-based significance comparisons.

References

The present analysis does not, however, determine whether this behavior is caused specifically by the treatment of fiber assignment, by other differences in the mock construction, or by the covariance model itself.

— A Finely-Binned Measurement of the Connected Even-Parity Galaxy 4-Point Correlation Function of DESI Year 1 Luminous Red Galaxies  (2609.09340 - Leonard et al., 8 Sep 2026) in Section 4.2, subsection “4PCF Detection with Analytic Covariance”

Determining whether the discrepancies identified here can be associated with particular ingredients of the galaxy--halo model will require dedicated mock comparisons and is left for future work.

— A Finely-Binned Measurement of the Connected Even-Parity Galaxy 4-Point Correlation Function of DESI Year 1 Luminous Red Galaxies  (2609.09340 - Leonard et al., 8 Sep 2026) in Section Discussion and Conclusions

The residual offsets found in the verification test are not attributed to the neutrino treatment or to the difference in the fiducial cosmologies, and whether those differences contribute to them has not been established.

— Model-independent parameters from DESI DR1 LRG2 with an explicitly varying power-spectrum shape  (2610.21235 - Song et al., 15 Oct 2026) in Section 2, subsection “Verification test for Single-template data analysis”