N-flation with Hierarchically Light Axions in String Compactifications

TL;DR

The paper presents an explicit string-theoretic realization of axionic N-flation within the LARGE Volume Scenario of type IIB compactifications. By stabilising the bulk Kahler moduli perturbatively and keeping a set of $N$ axions light via subleading non-perturbative effects, it achieves a controlled hierarchy between heavy moduli and inflaton-like axions. The construction yields high-scale supersymmetry breaking, a viable perturbative reheating mechanism, and a tunable route to quintessence by volume adjustment. It also highlights major challenges, notably backreaction from a large number of species, in realizing a fully explicit embedding. Overall, the work provides a concrete path to incorporating multi-axion inflation and late-time acceleration within a UV-complete string framework.

Abstract

We present an explicit embedding of axionic N-flation in type IIB string compactifications where most of the Kahler moduli are stabilised by perturbative effects, and so are hierarchically heavier than the corresponding N >> 1 axions whose collective dynamics drives inflation. This is achieved in the framework of the LARGE Volume Scenario for moduli stabilisation. Our set-up can be used to realise a model of either inflation or quintessence, just by varying the volume of the internal space which controls the scale of the axionic potential. Both cases predict a very high scale of supersymmetry breaking. A viable reheating of the Standard Model degrees of freedom can be achieved after the end of inflation due to the perturbative decay of the N light axions which drive inflation.