On Background Independence in String Theory

TL;DR

This paper explores the challenge of achieving background independence in string theory, highlighting a conflict with duality invariance and proposing that enhanced gauge symmetries are necessary for a consistent formulation.

Contribution

It identifies a fundamental conflict between background independence and duality invariance in string theory and suggests that new gauge degrees of freedom are needed for a consistent, background-independent formulation.

Findings

Conflict between background independence and duality invariance when higher-derivative corrections are included

Resolution involves introducing new gauge degrees of freedom

Enhanced gauge symmetries are necessary for a manifestly background independent string theory

Abstract

I discuss various aspects of background independence in the context of string theory, for which so far we have no manifestly background independent formulation. After reviewing the role of background independence in classical Einstein gravity, I discuss recent results implying that there is a conflict in string theory between manifest background independence and manifest duality invariance when higher-derivative corrections are included. The resolution of this conflict requires the introduction of new gauge degrees of freedom together with an enlarged gauge symmetry. This suggests more generally that a manifestly background independent and duality invariant formulation of string theory requires significantly enhanced gauge symmetries.