Non-Abelian coset string backgrounds from asymptotic and initial data

TL;DR

The paper constructs hierarchies of exact string backgrounds using non-Abelian cosets and gauged WZW models, demonstrating their properties to all orders in 1' and exploring potential cosmological implications.

Contribution

It introduces a hierarchy of string backgrounds derived from non-Abelian cosets, with boundary properties linked across the hierarchy and proven to hold to all orders in 1'.

Findings

Hierarchies of exact string backgrounds are constructed from non-Abelian cosets.

Boundary backgrounds of higher hierarchy members generate the backgrounds of the next.

The boundary can be time-like or space-like, with potential cosmological applications.

Abstract

We describe hierarchies of exact string backgrounds obtained as non-Abelian cosets of orthogonal groups and having a space--time realization in terms of gauged WZW models. For each member in these hierarchies, the target-space backgrounds are generated by the ``boundary'' backgrounds of the next member. We explicitly demonstrate that this property holds to all orders in $\alpha'$. It is a consequence of the existence of an integrable marginal operator build on, generically, non-Abelian parafermion bilinears. These are dressed with the dilaton supported by the extra radial dimension, whose asymptotic value defines the boundary. Depending on the hierarchy, this boundary can be time-like or space-like with, in the latter case, potential cosmological applications.