Phenomenological approaches of inflation and their equivalence

Abstract

In this work, we analyze two possible alternative and model-independent approaches to describe the inflationary period. The first one assumes a general equation of state during inflation due to Mukhanov, while the second one is based on the slow-roll hierarchy suggested by Hoffman and Turner. We find that, remarkably, the two approaches are equivalent from the observational viewpoint, as they single out the same areas in the parameter space, and agree with the inflationary attractors where successful inflation occurs. Rephrased in terms of the familiar picture of a slowly rolling, canonically normalized scalar field, the resulting inflaton excursions in these two approaches are almost identical. Furthermore, once the Galactic dust polarization data from Planck are included in the numerical fits, inflaton excursions can safely take sub-Planckian values.

arXiv commentRevtex, 8 pages, 4 figures. References updated. Matches published version in PRD

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• Primordial power spectrum features in phenomenological descriptions of inflation
• The Reconstruction of Non-Minimal Derivative Coupling Inflationary Potentials
• Inflationary attractors from a non-canonical kinetic term
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• Returning Back to Mukhanov Parametrization of Inflationary Equation of State
• Confronting Mukhanov Parametrization of Inflationary Equation-of-State with ACT-DR6