# Study in the noncanonical domain of Goldstone inflation

## TL;DR

This paper explores a noncanonical Goldstone inflation model, including natural inflation as a special case, and compares its predictions with Planck data, also analyzing reheating constraints post-inflation.

## Contribution

It extends Goldstone inflation to the noncanonical domain, providing observational viability and reheating constraints, which is a novel analysis in this context.

## Key findings

- Noncanonical Goldstone inflation can satisfy current observational bounds.
- Reheating temperature and e-folds are constrained by inflationary parameters.
- Natural inflation is recovered as a limiting case in the noncanonical regime.

## Abstract

Recent observations of the cosmic microwave background (CMB) indicate that a successful theory of cosmological inflation needs to have flat potential of the inflaton scalar field. Realizing the inflaton to be a pseudo-Nambu Goldstone boson (pNGB) could ensure the 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, and studied the model in the noncanonical domain. Natural inflation is a limiting case of this model, which is also studied here in the noncanonical regime. Our result is compared with the recent release by Planck collaboration and it is shown that for some combination of the model parameters, a Goldstone inflationary model in the noncanonical realisation obeys the current observational bounds. Then, we studied the era of reheating after the end of inflation. For different choice of model parameters, constraints on the reheating temperature ($T_{\rm re}$) and number of e-folds during reheating($N_{\rm re}$) for the allowed inflationary observables (e.g. scalar spectral index($n_s$) and tensor to scalar ratio($r$)) are predicted for this model.