Sigma-Eight at the Percent Level: The EFT Likelihood in Real Space

Abstract

The effective field theory likelihood for the density field of biased tracers allows for cosmology inference from the clustering of galaxies that consistently uses all available information at a given order in perturbation theory. This paper presents results and implementation details on the real-space (as opposed to Fourier-space) formulation of the likelihood, which allows for the incorporation of survey window functions. The implementation further uses a Lagrangian forward model for biased tracers which automatically accounts for all relevant contributions up to any desired order. Unbiased inference of $σ_8$ is demonstrated at the 2% level for cutoff values $Λ\leq 0.14h\,{\rm Mpc}^{-1}$ for halo samples over a range of masses and redshifts. The inferred value shows the expected convergence to the ground truth in the low-cutoff limit. Apart from the possibility of including observational effects, this represents further substantial improvement over previous results based on the EFT likelihood.