On (de Sitter) Vacua in Heterotic String Theory

TL;DR

This paper reviews recent progress in heterotic string theory vacua, discusses no-go theorems for de Sitter solutions, and explores a potential loophole involving non-perturbative corrections that could enable de Sitter vacua.

Contribution

It introduces a possible way to realize de Sitter vacua in heterotic string theory through non-perturbative, dilaton-dependent corrections to the Kähler potential.

Findings

Recent heterotic model building advances

Proofs of de Sitter no-go theorems

Potential loophole via non-BPS heterotic instantons

Abstract

Heterotic toroidal orbifolds are a powerful framework for testing our understanding of string vacua. We review recent advances in heterotic model building, from constructing new vacua to proving novel de Sitter no-go theorems. We also illustrate a potential loophole that could pave the way for the realisation of de Sitter vacua within heterotic string theories. This involves the introduction of non-perturbative, stringy, dilaton-dependent corrections to the K\"ahler potential. We discuss how recently found non-BPS heterotic instantons might provide the necessary corrections.