Initial conditions and sampling for multifield inflation

TL;DR

This paper examines the initial conditions necessary for multifield inflation, highlighting the chaotic pre-inflationary dynamics and analyzing how initial data influence the onset of inflation, with a focus on hybrid inflation models.

Contribution

It provides a comprehensive analysis of initial conditions in multifield inflation, introducing fixed energy comparisons and exploring the structure of successful initial conditions.

Findings

Long-range order in successful initial conditions

Effective smoothing scale for fractal initial conditions

Impact of prior information on initial data selection

Abstract

We investigate the initial conditions problem for multifield inflation. In these scenarios the pre-inflationary dynamics can be chaotic, increasing the sensitivity of the onset of inflation to the initial data even in the homogeneous limit. To analyze physically equivalent scenarios we compare initial conditions at fixed energy. This ensures that each trajectory is counted once and only once, since the energy density decreases monotonically. We present a full analysis of hybrid inflation that reveals a greater degree of long range order in the set of "successful" initial conditions than was previously apparent. We explore the effective smoothing scale for the fractal set of successful initial conditions induced by the finite duration of the pre-inflationary phase. The role of the prior information used to specify the initial data is discussed in terms of Bayesian sampling.