Non-local symmetries of the closed N=2 string

TL;DR

This paper identifies an infinite set of non-local symmetries in the closed N=2 string, linking them to the Plebanski equation and deriving a vanishing theorem for certain correlation functions.

Contribution

It reveals the non-local symmetries of the closed N=2 string and connects them to the Plebanski equation, providing new insights into its structure and correlation functions.

Findings

Identified infinite non-local symmetries of the closed N=2 string.

Linked symmetry transformations to the linearised non-local symmetries of the Plebanski equation.

Rederived the vanishing theorem for tree-level correlation functions with more than three external legs.

Abstract

By carefully analysing the picture-dependence of the BRST cohomology an infinite set of symmetry charges of the closed N=2 string is identified. The transformation laws of the physical vertex operators are shown to coincide with the linearised non-local symmetries of the Plebanski equation (which is the effective field theory of the closed N=2 string). Moreover, the corresponding Ward identities are powerful enough to allow for a rederivation of the well known vanishing theorem for the tree-level correlation functions with more than three external legs.