Scale-dependent bias from multiple-field inflation

TL;DR

This paper derives a formula for the scale-dependent bias in the inflationary bispectrum's squeezed limit, enabling predictions for multi-field inflation models relevant to upcoming galaxy surveys.

Contribution

It provides the first generic formula for the bispectrum scaling in multi-field inflation, linking inflationary physics to observable galaxy bias.

Findings

Formula for bispectrum scaling in multi-field inflation

Predicts halo bias at low wavenumber

Applicable to next-generation galaxy surveys

Abstract

We provide a formula for the scaling behaviour of the inflationary bispectrum in the 'squeezed' limit where one momentum becomes much smaller than the other two. This determines the scaling of the halo bias at low wavenumber and will be an important observable for the next generation of galaxy surveys. Our formula allows it to be predicted for the first time for a generic inflationary model with multiple light, canonically-normalized scalar fields.