Study of Goldstone Inflation in the domain of Einstein-Gauss-Bonnet gravity

TL;DR

This paper explores Goldstone inflation within Einstein-Gauss-Bonnet gravity, demonstrating that the model aligns well with observational data and offers a rich phenomenology for inflation and reheating phases.

Contribution

It extends Goldstone inflation models to Einstein-Gauss-Bonnet gravity, showing improved compatibility with observations and detailed reheating analysis.

Findings

Inflationary observables match Planck 2018 data

EGB coupling enhances model viability without fine tuning

Reheating dynamics depend on model parameters

Abstract

Realizing the inflationary epoch driven by a pseudo-Nambu Goldstone boson (pNGB) could ensure the coveted flatness, and the sub-Planckian scales related to the dynamics of the paradigm. In this work, we have taken the most general form of such a scenario: Goldstone inflation proposed in \cite{croon}, and studied the model in Einstein-Gauss-Bonnet gravity. Natural inflation is a limiting case of this model, is also studied here. The specific form of the EGB coupling gives ample opportunity to study the rich phenomenology associated with inflation as well as the reheating epoch. Predicted values of the inflationary observables, tensor to scalar ratio ($r$), and spectral index ($n_s$) are in good agreement with the recent observations from $Planck'18$ \cite{Planck2018}. Thus, in the framework of EGB one can resurrect the model, which otherwise needs quite a bit of fine tuning or diversion from the canonical domain as studied in \cite{Bhattacharya:2018xlw}, to survive in the standard cold inflationary scenario. Finally, the era of reheating is studied for different choice of model parameters.