Joining-splitting interaction of non-critical string

TL;DR

This paper extends the Mandelstam method to analyze the joining-splitting interactions of non-critical bosonic strings in the light-cone formulation, exploring Lorentz covariance and unitarity in non-critical dimensions.

Contribution

It introduces an extension of the Mandelstam method for non-critical string models and derives conditions for Lorentz covariance involving Liouville excitations.

Findings

Covariant and light-cone approaches are equivalent in non-critical dimensions.

Conditions for Lorentz covariance are established.

Discussion on unitarity aspects of non-critical string theory.

Abstract

The joining--splitting interaction of non-critical bosonic string is analyzed in the light-cone formulation. The Mandelstam method of constructing tree string amplitudes is extended to the bosonic massive string models of the discrete series. The general properties of the Liouville longitudinal excitations which are necessary and sufficient for the Lorentz covariance of the light-cone amplitudes are derived. The results suggest that the covariant and the light-cone approach are equivalent also in the non-critical dimensions. Some aspects of unitarity of interacting non-critical massive string theory are discussed.