Non-Perturbative Formulation of Time-Dependent String Solutions

TL;DR

This paper introduces a non-perturbative world-sheet renormalization-group method for bosonic strings, revealing a new time-dependent background solution that could impact cosmological models and is conformally invariant to all orders.

Contribution

It presents a novel non-perturbative technique for string theory and discovers a new time-dependent background solution with potential cosmological applications.

Findings

New non-perturbative string background solution

Demonstration of conformal invariance to all orders in alpha'

Potential relevance to early universe cosmology

Abstract

We formulate here a new world-sheet renormalization-group technique for the bosonic string, which is non-perturbative in the Regge slope alpha' and based on a functional method for controlling the quantum fluctuations, whose magnitudes are scaled by the value of alpha'. Using this technique we exhibit, in addition to the well-known linear-dilaton cosmology, a new, non-perturbative time-dependent background solution. Using the reparametrization invariance of the string S-matrix, we demonstrate that this solution is conformally invariant to alpha', and we give a heuristic inductive argument that conformal invariance can be maintained to all orders in alpha'. This new time-dependent string solution may be applicable to primordial cosmology or to the exit from linear-dilaton cosmology at large times.