N-flation

TL;DR

The paper introduces N-flation, a radiatively stable, UV-consistent realization of chaotic inflation in which $N$ axions with independent shift symmetries collectively drive slow-roll dynamics via a radial mode. It analyzes radiative stability both in non-supersymmetric and supersymmetric contexts and shows that a dense axion spectrum supports self-damping without fine-tuning; it also embeds the construction in string theory, discussing decay constants and moduli stabilization. String-theory corrections to Newton's constant place bounds on the achievable number of e-foldings, though favorable topologies can permit substantial inflation. The resulting inflationary observables reproduce the standard chaotic $m^2\phi^2$ predictions, with manageable reheating and a naturally suppressed gravitino problem. Overall, N-flation offers a radiatively controlled, UV-complete path to chaotic inflation within string theory.

Abstract

The presence of many axion fields in four-dimensional string vacua can lead to a simple, radiatively stable realization of chaotic inflation.