Model-Building for Fractional Superstrings

TL;DR

This paper explores model-building for fractional superstrings, a new class of string theories with lower critical dimensions, revealing their relation to traditional heterotic strings and their natural compactifications.

Contribution

It establishes a correspondence between fractional superstring models and certain heterotic string models, enabling partition function generation and insights into their compactifications.

Findings

Fractional superstrings have fewer models than expected.

They can be naturally compactified to lower dimensions.

The six-dimensional fractional superstring relates to four-dimensional spacetime.

Abstract

Fractional superstrings are recently-proposed generalizations of the traditional superstrings and heterotic strings. They have critical spacetime dimensions which are less than ten, and in this paper we investigate model-building for the heterotic versions of these new theories. We concentrate on the cases with critical spacetime dimensions four and six, and find that a correspondence can be drawn between the new fractional superstring models and a special subset of the traditional heterotic string models. This allows us to generate the partition functions of the new models, and demonstrate that their number is indeed relatively limited. It also appears that these strings have uniquely natural compactifications to lower dimensions. In particular, the fractional superstring with critical dimension six has a natural interpretation in four-dimensional spacetime.