Perturbation Theory in Two Dimensional Open String Field Theory

TL;DR

This paper develops a covariant string field theory framework for open 2D strings, calculating low-order tachyon amplitudes and confirming their consistency with previous bulk amplitude results, while clarifying their pole structure.

Contribution

It introduces a covariant formalism for open 2D string field theory and explicitly computes low-order amplitudes, aligning with known results and clarifying amplitude structures.

Findings

Calculated 4- and 5-point tachyon amplitudes

Confirmed agreement with previous bulk amplitude calculations

Clarified the pole structure and origin from higher string modes

Abstract

In this paper we develop the covariant string field theory approach to open 2d strings. Upon constructing the vertices, we apply the formalism to calculate the lowest order contributions to the 4- and 5- point tachyon--tachyon tree amplitudes. Our results are shown to match the `bulk' amplitude calculations of Bershadsky and Kutasov. In the present approach the pole structure of the amplitudes becomes manifest and their origin as coming from the higher string modes transparent.