Moduli Stabilization with the String Higgs Effect

TL;DR

The paper addresses the cosmological moduli problem by leveraging the string Higgs effect at enhanced symmetry points to dynamically stabilize the radion at the self-dual radius $R=\sqrt{\alpha^{\prime}}$. It develops the spectrum and Higgs-like mass generation near ESPs, then derives an effective radion potential from backreaction of ESP states in a time-dependent background, with stabilization aided by Hubble friction. The mechanism provides a concrete route to fix the compactification scale and suggests compatibility with brane inflation or flux compactifications, pending incorporation of non-Abelian interactions and explicit model-building. Overall, it highlights the necessity of including ESP states in low-energy actions and offers a cosmology-friendly path to moduli stabilization in string theory.

Abstract

We review the notion of the Higgs effect in the context of string theory. We find that by including this effect in time dependent backgrounds, one is led to a natural mechanism for stabilizing moduli at points of enhanced gauge symmetry. We consider this mechanism for the case of the radion (size of the extra dimensions) and find that as decompactification of the large spatial dimensions takes place the radion will remain stabilized at the self dual radius. We discuss how this mechanism can be incorporated into models of string cosmology and brane inflation to resolve some outstanding problems. We also address some issues regarding which string states should be included when constructing low energy actions in string cosmology.