Amplitudes for left-handed strings

TL;DR

This paper explores a class of left-handed string models with massless states and manifest T-duality, demonstrating how to compute amplitudes using gauge parameters as infrared regulators, connecting to known string formalisms.

Contribution

It introduces a method to calculate amplitudes in left-handed string models using gauge parameters as infrared regulators, linking to the Mason-Skinner formalism and zero-tension limits.

Findings

Amplitudes produce CHY delta-functions after modular integration.

Zero-tension limit yields Mason-Skinner string-like action.

Without the limit, amplitudes face similar issues as in Mason-Skinner formalism.

Abstract

We consider a class of string-like models introduced previously where all modes are left-handed, all states are massless, T-duality is manifest, and only a finite number of orders in the string tension can appear. These theories arise from standard string theories by a singular gauge limit and associated change in worldsheet boundary conditions. In this paper we show how to calculate amplitudes by using the gauge parameter as an infrared regulator. The amplitudes produce the Cachazo-He-Yuan delta-functions after some modular integration; the Mason-Skinner string-like action and amplitudes arise from the zero-tension (infinite-slope) limit. However, without the limit the amplitudes have the same problems as found in the Mason-Skinner formalism.