Can the string scale be related to the cosmic baryon asymmetry?

TL;DR

This paper explores a string theory-based mechanism linking the string scale to cosmic baryon asymmetry, using the Green-Schwarz mechanism and axions to generate and constrain lepton asymmetry during inflation.

Contribution

It provides a string embedding of a baryogenesis mechanism via the Green-Schwarz mechanism, connecting string scale, axions, and gravitational waves to baryon asymmetry.

Findings

String scale and coupling can be observationally constrained.

Axion-driven gravitational waves can generate lepton asymmetry.

The mechanism is embedded within string theory via the Green-Schwarz mechanism.

Abstract

In a previous work, a mechanism was presented by which baryon asymmetry can be generated during inflation from elliptically polarized gravitons. Nonetheless, the mechanism only generated a realistic baryon asymmetry under special circumstances which requires an enhancement of the lepton number from an unspecified GUT. In this note we provide a stringy embedding of this mechanism through the Green-Schwarz mechanism, demonstrating that if the model-independent axion is the source of the gravitational waves responsible for the lepton asymmetry, one can observationally constrain the string scale and coupling.