World Sheet and Space Time Physics in Two Dimensional (Super) String Theory

TL;DR

This paper analyzes the structure of tree-level tachyon scattering amplitudes in two-dimensional (super) string theory, revealing simplifications and analytic structures that enhance understanding of space-time physics in this simplified setting.

Contribution

It demonstrates the simplified structure of resonant amplitudes in 2D (super) string theory and relates non-resonant amplitudes to these, providing explicit calculations and space-time interpretations.

Findings

Resonant amplitudes exhibit a simple structure due to decoupling of discrete states.

Non-resonant amplitudes are determined by resonant ones.

Explicit calculations reveal interesting analytic properties.

Abstract

We show that tree level ``resonant'' $N$ tachyon scattering amplitudes, which define a sensible ``bulk'' S -- matrix in critical (super) string theory in any dimension, have a simple structure in two dimensional space time, due to partial decoupling of a certain infinite set of discrete states. We also argue that the general (non resonant) amplitudes are determined by the resonant ones, and calculate them explicitly, finding an interesting analytic structure. Finally, we discuss the space time interpretation of our results.