Covariant N=2 heterotic string in four dimensions

TL;DR

This paper develops a covariant formulation of the heterotic superstring with N=2 supersymmetry in four dimensions, connecting it to projective superspace and N=2 supergravity, enabling new approaches to string field theories.

Contribution

It introduces a covariant, manifest N=2 supersymmetric heterotic string formulation on K3×T^2, linking projective superspace to string theory and supergravity.

Findings

Manifest N=2 supersymmetry in heterotic string on K3×T^2

Natural emergence of projective superspace in the hybrid formulation

Potential for new descriptions of supersymmetric field theories

Abstract

We construct a covariant formulation of the heterotic superstring on K3 times T^2 with manifest N=2 supersymmetry. We show how projective superspace appears naturally in the hybrid formulation giving a (partially) geometric interpretation of the harmonic parameter. The low-energy effective action for this theory is given by a non-standard form of N=2 supergravity which is intimately related to the N=1 old-minimal formulation. This formalism can be used to derive new descriptions of interacting projective superspace field theories using Berkovits' open string field theory and the the heterotic Berkovits-Okawa-Zwiebach construction.