On String Field Theory and Effective Actions

TL;DR

This paper compares a truncation of string field theory with the duality invariant effective action of four-dimensional N=4 heterotic strings, exploring compatibility conditions and implications for background independence and underlying symmetries.

Contribution

It establishes conditions under which cyclic three-string vertices are compatible with the effective field theory, advancing understanding of string field theory's structure and symmetries.

Findings

Cyclic three-string vertices are compatible with the D=4, N=4 effective field theory.

The effective actions can shed light on the non-polynomial structure of covariant closed string field theory.

Discussion of the effective action and string field theory for N=2 strings.

Abstract

A truncation of string field theory is compared with the duality invariant effective action of $D=4, N=4$ heterotic strings to cubic order. The three string vertex must satisfy a set of compatibility conditions. Any cyclic three string vertex is compatible with the $D=4, N=4$ effective field theory. The effective actions may be useful in understanding the non--polynomial structure and the underlying symmetry of covariant closed string field theory, and in addressing issues of background independence. We also discuss the effective action and string field theory of the $N=2$ string.