General String Cosmologies at Order $\alpha'{}^{\,3}$

TL;DR

This paper computes the cosmological reductions of various string theories up to order  derivatives, refining methods to achieve a canonical form compatible with continuous duality symmetries.

Contribution

It extends previous reduction techniques to higher derivative orders and ensures compatibility with duality invariances across different string theories.

Findings

Unified framework for cosmological reductions up to  derivatives

Refined methods for canonical form of reduced theories

Compatibility with continuous $O(d,d,\,\mathbb{R})$ invariance

Abstract

We compute the cosmological reduction of general string theories, including bosonic, heterotic and type II string theory to order $\alpha'^{3}$, i.e., with up to eight derivatives. To this end we refine recently introduced methods that allow one to bring the reduced theory in one dimension to a canonical form with only first-order time derivatives. The resulting theories are compatible with a continuous $O(d,d,\mathbb{R})$ invariance, which in turn fixes the B-field couplings.