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Title: Saving Natural Inflation

Slow-roll inflation requires the inflaton field to have an exceptionally flat potential, which combined with measurements of the scale of inflation demands some degree of fine-tuning. Alternatively, the flatness of the potential could be due to the inflaton's origin as a pseudo-Goldstone boson, as in Natural Inflation. Alas, consistency with Planck data places the original proposal of Natural Inflation in a tight spot, as it requires a trans-Planckian excursion of the inflaton. Although one can still tune the renormalizable potential to sub-Planckian values, higher order corrections from quantum gravity or sources of breaking of the Goldstone symmetry would ruin the predictivity of the model. In this paper we show how in more realistic models of Natural Inflation one could achieve inflation without a trans-Planckian excursion of the field. We show how a variant of Extra-natural inflation with bulk fermions can achieve the desired goal and discuss its four-dimensional duals. We also present a new type of four dimensional models inspired in Little Higgs and Composite Higgs models which can lead to sub-Planckian values of the inflaton field.
Authors:
;  [1]
  1. Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom)
Publication Date:
OSTI Identifier:
22382000
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2015; Journal Issue: 02; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CORRECTIONS; COSMOLOGICAL INFLATION; FERMIONS; GOLDSTONE BOSONS; HIGGS BOSONS; HIGGS MODEL; ORIGIN; QUANTUM GRAVITY; RENORMALIZATION