A no-go theorem for monodromy inflation

TL;DR

This work analyzes whether the monodromy inflation mechanism of Silverstein and Westphal can be realized in a concrete type IIA compactification. By enforcing a warped 10D background with D4/O4 sources on a solvmanifold containing the nilmanifold N3, the author derives a no-go theorem that forbids AdS and Minkowski vacua and imposes a phenomenologically unacceptable lower bound on de Sitter vacua. The obstruction arises from a fundamental tension between the wrapped brane geometry and the internal manifold’s curvature, implying the mechanism cannot be embedded in this standard compactification framework. The results have broad implications for axion monodromy models and underscore the need for alternative ingredients or settings to realize such inflationary scenarios in string theory.

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.