Taming the Runaway Problem of Inflationary Landscapes

TL;DR

This paper addresses the runaway problem in inflationary landscapes by proposing a solution that constrains the probability of universe parameters, with implications for reheating temperature, CP violation, and supersymmetry.

Contribution

It introduces a general solution to the runaway problem in inflationary landscapes and applies it to specific cosmological scenarios, deriving testable predictions.

Findings

Upper bound on reheating temperature in our universe

Predictions for CP violating phases and neutrinoless double beta decay

Constraints on the fundamental scale of supersymmetry breaking

Abstract

A wide variety of vacua, and their cosmological realization, may provide an explanation for the apparently anthropic choices of some parameters of particle physics and cosmology. If the probability on various parameters is weighted by volume, a flat potential for slow-roll inflation is also naturally understood, since the flatter the potential the larger the volume of the sub-universe. However, such inflationary landscapes have a serious problem, predicting an environment that makes it exponentially hard for observers to exist and giving an exponentially small probability for a moderate universe like ours. A general solution to this problem is proposed, and is illustrated in the context of inflaton decay and leptogenesis, leading to an upper bound on the reheating temperature in our sub-universe. In a particular scenario of chaotic inflation and non-thermal leptogenesis, predictions can be made for the size of CP violating phases, the rate of neutrinoless double beta decay and, in the case of theories with gauge-mediated weak scale supersymmetry, for the fundamental scale of supersymmetry breaking.