Cris Sabiu, "Climbing the N-point Ladder: Breaking Degeneracies between Cosmology and Halo Model"

Tuesday 11 Aug 2026, 16:00 → 18:00 Asia/Seoul

The galaxy two-point function leaves much of the cosmological information in the nonlinear density field untapped. Higher-order clustering statistics recover it, but their promise for real surveys rests on whether that information survives our ignorance of how galaxies occupy dark matter halos. I will present a configuration-space Fisher forecast built on the connected four-point correlation function (4PCF) measured on the Quijote simulations with the GPU N-point estimator GRAMSCI.

For dark matter halos, adding the connected 4PCF to the two- and three-point functions tightens ΛCDM and Neutrino (Mν) constraints by roughly 50% and helps break the σ₈–Mν degeneracy, because its information lies along complementary directions. I then repeat the analysis on HOD galaxy mocks, marginalizing over a realistic galaxy–halo model: halo occupation, satellite velocity bias, and assembly bias. The central result is that the connected-4PCF information gain persists, and for some parameters even grows, under this full marginalization, yielding a neutrino-mass forecast robust to galaxy-formation systematics. Configuration-space higher-order clustering thus emerges as a genuinely robust probe for Stage-IV spectroscopic surveys. Our result are available: https://arxiv.org/abs/2607.09116