The Twisted String Vertex Algorithm Applied to the $Z_2$-Twisted Scalar String Four Vertex

TL;DR

This paper extends a recent algorithm for calculating four-string vertices to include Z2-twisted scalars, deriving the full propagator on the Riemann sphere with branch cuts and discussing its relation to existing results.

Contribution

The paper applies an existing algorithm to Z2-twisted scalars and derives the full scalar propagator on the Riemann sphere with branch cuts.

Findings

Derived the full propagator for Z2-twisted scalars.

Extended the vertex algorithm to twisted scalar cases.

Connected results to previous literature.

Abstract

Recently an algorithm was found by means of which one can calculate terms at arbitrary oscillator level in the four-Ramond vertex obtained by sewing. Here we show that this algorithm is applicable also to the case of ${\bf Z}_2$-twisted scalars and derive the full propagator for scalars on the Riemann sphere with two branch cuts. The relation to similar results previously derived in the literature by other means is discussed briefly.