A no-go theorem for monodromy inflation

TL;DR

This paper proves a no-go theorem showing that embedding monodromy inflation in certain string theory compactifications cannot produce suitable vacua, challenging the viability of this inflation model.

Contribution

It provides a rigorous ten-dimensional no-go theorem that rules out the existence of suitable vacua for monodromy inflation in type IIA supergravity.

Findings

Anti-de Sitter and Minkowski vacua are impossible.

De Sitter vacua exist but have too high a cosmological constant.

The results constrain string theory models of inflation.

Abstract

We study the embedding of the monodromy inflation mechanism by E. Silverstein and A. Westphal (2008) in a concrete compactification setting. To that end, we look for an appropriate vacuum of type IIA supergravity, corresponding to the minimum of the inflaton potential. We prove a no-go theorem on the existence of such a vacuum, using ten-dimensional equations of motion. Anti-de Sitter and Minkowski vacua are ruled out; de Sitter vacua are not excluded, but have a lower bound on their cosmological constant which is too high for phenomenology.