Testing Superstring Theories with Gravitational Waves

TL;DR

This paper proposes a method to test superstring theories using gravitational wave observations, linking early universe dynamics with string compactifications and scalar fields.

Contribution

It introduces a transfer function connecting early matter domination to gravitational wave signals, enabling testing of superstring compactifications via inflationary gravitational waves.

Findings

A transfer function for early matter era effects on gravitational waves

Potential to test superstring compactifications with gravitational wave data

Applicable to models with scalar fields of specific mass and interaction properties

Abstract

We provide a simple transfer function that determines the effect of an early matter dominated era on the gravitational wave background and show that a large class of compactifications of superstring theory might be tested by observations of the gravitational wave background from inflation. For large enough reheating temperatures $> 10^9 \GeV$ the test applies to all models containing at least one scalar with mass $< 10^{12}\GeV$ that acquires a large initial oscillation amplitude after inflation and has only gravitational interaction strength, i.e., a field with the typical properties of a modulus.