An improved fitting formula for the dark matter bispectrum

TL;DR

This paper introduces an improved analytic fitting formula for the dark matter bispectrum in LCDM cosmology, calibrated with simulations, achieving high accuracy across relevant scales and redshifts.

Contribution

The paper presents a new fitting formula for the dark matter bispectrum that improves accuracy over previous models by calibration with simulations across multiple scales and redshifts.

Findings

Deviation less than 5% across tested scales

Fits well to BAO features

Reliable predictions for non-linear dark matter bispectrum

Abstract

In this paper we present an improved fitting formula for the dark matter bispectrum motivated by the previous phenomenological approach of Scoccimarro & Couchman (2001). We use a set of LCDM simulations to calibrate the fitting parameters in the k-range of 0.03 h/Mpc<k<0.4 h/Mpc and in the redshift range of 0<z<1.5. This new proposed fit describes well the BAO-features although it was not designed to. The deviation between the simulations output and our analytic prediction is typically less than 5% and in the worst case is never above 10%. We envision that this new analytic fitting formula will be very useful in providing reliable predictions for the non-linear dark matter bispectrum for LCDM models.