Reheating and relic gravitational waves as remedies for degeneracies of non-canonical natural inflation

TL;DR

This paper investigates a non-canonical inflation model, showing that relic gravitational waves can help resolve parameter degeneracies that are not broken by reheating constraints alone.

Contribution

It demonstrates that relic gravitational wave spectra can break degeneracies in inflationary parameters that reheating constraints cannot resolve.

Findings

Relic gravitational waves help break degeneracies in model parameters.

Reheating parameters alone are insufficient to resolve all degeneracies.

Allowed ranges for inflation duration and parameters are constrained by observational data.

Abstract

Here, a natural non-canonical inflationary model based on a power-law Lagrangian is investigated. We analyze the scalar spectral index $n_{\rm s}$ and the tensor-to-scalar ratio $r$ of the model and identify their degeneracies with respect to the free parameters. Notably, $n_{\rm s}$ and $r$ show effective independence from the model parameters due to degeneracies in the slow-roll parameters that leads to unresolved parameter degeneracies. Employing the constraints on reheating parameters such as the reheating duration $N_{\rm{reh}}$, the reheating temperature $T_{\rm{reh}}$, and the equation of state parameter $\omega_{\rm{reh}}$, is found to be insufficient to fully break these degeneracies. However, the relic gravitational wave spectrum provides a way to break degeneracy with respect to the non-canonical parameter $\alpha$, degeneracy with respect to the potential parameter $f$ persist. Finally, we specify the allowed ranges for the inflationary duration $N$ and the parameter $\alpha$, in light of the latest observational data. These results highlight the role of relic gravitational waves in refining inflationary models and illustrate the challenges in fully resolving parameter degeneracies.