Chern-Simons Inflation and Baryogenesis

TL;DR

This paper proposes a novel inflation model driven by gauge fields and fermionic charge interactions, which also naturally generates lepton asymmetry and baryogenesis during inflation.

Contribution

It introduces a new inflationary framework based on Chern-Simons interactions with fermionic charges, linking inflation dynamics to baryogenesis mechanisms.

Findings

Inflation driven by gauge field and fermionic charge interaction remains constant during inflation.

A mechanism for lepton asymmetry generation via pseudo scalar coupling to Chern-Simons term.

Model predicts sufficient e-folds and baryon asymmetry consistent with observations.

Abstract

We present a model of inflation based on the interaction between a homogeneous and isotropic configuration of a U(1) gauge field and fermionic charge density $\mathcal{J}_{0}$. The regulated fermionic charge density is generated from a Bunch-Davies vacuum state using the methods of Koksma and Prokopec \cite{Koksma:2009tc}, and is found to redshift as $1/a(\eta)$. The time-like component of gauge field is sourced by the fermionic charge leading to a growth in the gauge field $A(\eta)_{0}\sim a(\eta)$. As a result inflation is dominated by the energy density contained in the gauge field and fermionic charge interaction, $A_{0}\, \mathcal{J}^{0}$, which remains constant during inflation. We also provide a mechanism to generate a net lepton asymmetry. The coupling of a pseudo scalar to the Chern-Simons term converts the gauge field fluctuations into lepton number and all three Sahkarov conditions are satisfied during inflation. Finally, the rapid oscillation of the pseudo scalar field near its minimum thermalizes the gauge field and ends inflation. We provide the necessary initial condition on the gauge field and fermionic charge to simultaneously generate enough e-folds and baryon asymmetry index.