Multi-Stream Inflation in a Landscape

TL;DR

This paper explores how inflation dynamics in a complex landscape with random features can lead to bifurcations in inflation trajectories, revealing phase transitions that influence observable features in the early universe.

Contribution

It introduces a probabilistic analysis of inflation trajectory bifurcations in a random potential landscape, highlighting phase transitions based on potential shape and bump spacing.

Findings

Bifurcation probability depends on potential bump shape and spacing.

Identifies a phase transition in bifurcation behavior.

Exponential amplification of isocurvature fluctuations near critical points.

Abstract

There are hidden observables for inflation, such as features localized in position space, which do not manifest themselves when only one inflation trajectory is considered. To address this issue, we investigate inflation dynamics in a landscape mimicked by a random potential. We calculate the probability for bifurcation of the inflation trajectory in multi-stream inflation. Depending on the shape of the random bumps and the distance between bumps in the potential, there is a phase transition: on one side of the critical curve in parameter space isocurvature fluctuation are exponentially amplified and bifurcation becomes very probable. On the other side bifurcation is dominated by a random walk where bifurcations are less likely to happen.