Constraints on Brane-World Inflation from the CMB Power Spectrum: Revisited

TL;DR

This paper revisits brane-world inflation models in light of recent CMB data, finding that most models are less compatible with observations, except for natural inflation which fits better due to modified e-folding constraints.

Contribution

It provides updated constraints on brane-world inflation models using the latest CMB data and explores their compatibility with various inflaton potentials.

Findings

Brane-world scenario generally increases the tensor-to-scalar ratio.

Most monomial potentials are disfavored in the brane-world context.

Natural inflation fits the data better in the brane-world scenario.

Abstract

We analyze the Randal Sundrum brane-world inflation scenario in the context of the latest CMB constraints from Planck. We summarize constraints on the most popular classes of models and explore some more realistic inflaton effective potentials. The constraint on standard inflationary parameters changes in the brane-world scenario. We confirm that in general the brane-world scenario increases the tensor-to-scalar ratio, thus making this paradigm less consistent with the Planck constraints. Indeed, when the BICEP2/Keck constraints are included, all monomial potentials in the brane-world scenario become disfavored compared to the standard scenario. However, for natural inflation the brane-world scenario fits the constraints better due to larger allowed values of the number of e-foldings N before the end of inflation in the brane-world.