Chiral Heterotic Strings with Positive Cosmological Constant

TL;DR

This paper constructs heterotic string models with spontaneously broken supersymmetry that naturally produce a small positive cosmological constant, influenced by string states beyond field theory expectations.

Contribution

It provides explicit semi-realistic heterotic string models with small supersymmetry breaking scales and positive cosmological constant, highlighting the role of massive string states.

Findings

Models achieve exponentially small positive cosmological constant.

Massive and non-level matched string states significantly affect the effective potential.

Conditions for dynamically ensuring desired properties are investigated.

Abstract

We present explicit examples of semi-realistic heterotic models with spontaneously broken supersymmetry, which dynamically lead to breaking scales much smaller than $M_{\rm Planck}$ and exponentially small positive values for the cosmological constant. Contrary to field theoretic intuition, we find that the global structure of the effective potential is significantly affected by contributions of massive and non-level matched string states and we investigate the conditions that dynamically ensure a number of desired properties.