Geometric Baryogenesis from Shift Symmetry

TL;DR

This paper proposes a novel baryogenesis mechanism driven by a Nambu-Goldstone boson, such as the QCD axion, which couples to spacetime and baryons, generating the universe's matter-antimatter asymmetry while potentially also explaining dark matter.

Contribution

It introduces a new geometric baryogenesis scenario utilizing shift symmetry and NG bosons, linking baryon asymmetry and dark matter in a unified framework.

Findings

NG boson coupling induces baryogenesis in early universe

QCD axion can generate baryon asymmetry and dark matter

Shift symmetry controls operator interactions in the model

Abstract

We present a new scenario for generating the baryon asymmetry of the universe that is induced by a Nambu-Goldstone (NG) boson. The shift symmetry naturally controls the operators in the theory, while allowing the NG boson to couple to the spacetime geometry as well as to the baryons. The cosmological background thus sources a coherent motion of the NG boson, which leads to baryogenesis. Good candidates of the baryon-generating NG boson are the QCD axion and axion-like fields. In these cases the axion induces baryogenesis in the early universe, and can also serve as dark matter in the late universe.