Light $U(1)$s in heterotic string models

TL;DR

This paper introduces a new string-derived $U(1)$ gauge symmetry that remains viable at low energies, addressing previous challenges and providing a framework for constructing consistent models.

Contribution

It proposes a novel $U(1)$ combination in heterotic string models that can survive to low scales, overcoming earlier difficulties.

Findings

A new $U(1)$ combination satisfying low-scale survival criteria

Analysis of previous string embedding attempts and their pitfalls

An example model demonstrating the framework's viability

Abstract

We present a novel string-derived $U(1)$ combination that satisfies necessary properties to survive to low scales. We discuss previous attempts at acquiring such an abelian gauge symmetry from two different string embeddings and the pitfalls associated with them. Finally, we give an example of how a satisfactory model may be constructed within our framework.