\$tring Theory and an Accelerating Universe

TL;DR

This paper explores how non-critical string theory can naturally explain an accelerating universe, linking vacuum energy to departures from criticality and illustrating a relaxation to zero vacuum energy akin to quintessence.

Contribution

It introduces a framework connecting non-critical string theory with cosmic acceleration and provides an explicit example of vacuum energy relaxation.

Findings

Non-critical string theory accommodates an accelerating universe.

Vacuum energy relates to departure from criticality.

Explicit example shows vacuum energy relaxes to zero.

Abstract

An accelerating Universe can be accommodated naturally within non-critical string theory, in which scattering is described by a superscattering matrix \$ that does not factorize as a product of $S$- and $S^\dagger$-matrix elements and time evolution is described by a modified Liouville equation characteristic of open quantum-mechanical systems. We describe briefly alternative representations in terms of the stochastic Ito and Fokker-Planck equations. The link between the vacuum energy and the departure from criticality is stressed. We give an explicit example in which non-marginal \$tring couplings cause a departure from criticality, and the corresponding cosmological vacuum energy relaxes to zero \`a la quintessence.