Locality in Free String Field Theory-II

TL;DR

This paper investigates the locality properties of covariant free bosonic string field theory, identifying strictly local covariant fields on an unconstrained space and approximately local observable fields on the physical space.

Contribution

It introduces covariant string fields that are strictly local on an unconstrained Hilbert space and defines observable fields that are approximately local on the physical Hilbert space.

Findings

Strictly local covariant string fields on unconstrained space

Observable fields are approximately local on physical space

Analysis of causality properties in string field theory

Abstract

We study the covariant free bosonic string field theory and explore its locality (causality) properties. We find covariant string fields which are strictly local and covariant, but act on an unconstrained Hilbert space with an indefinite inner product. From these we also define observable fields which act on the physical Hilbert space with an definite inner product. These are shown to be approximately local.