Interaction of d=2 c=1 Discrete States from String Field Theory

TL;DR

This paper analyzes off-shell tree amplitudes of discrete states in 2D gravity coupled to c=1 matter from string field theory, revealing pole structures and deriving an effective action constrained by Ward identities.

Contribution

It introduces a method to extract residues from off-shell amplitudes in string field theory, leading to a simple effective action for discrete states.

Findings

Residues are constrained by Ward identities.

Residues generate a simple effective action.

Pole structures in amplitudes are characterized.

Abstract

Starting from string field theory for 2d gravity coupled to c=1 matter we analyze the off-shell tree amplitudes of discrete states. The amplitudes exhibit the pole structure and we use the off-shell calculus to extract the residues and prove that just the residues are constrained by the Ward Identities. The residues generate a simple effective action.