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arXiv · 1806.05511

Natural Inflation with a periodic non-minimal coupling

Ricardo Z. Ferreira·Alessio Notari·Guillem Simeon
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Abstract

Natural inflation is an attractive model for primordial inflation, since the potential for the inflaton is of the pseudo Nambu-Goldstone form, $V(ϕ)=Λ^4 [1+\cos (ϕ/f)]$, and so is protected against radiative corrections. Successful inflation can be achieved if $f \gtrsim {\rm few}\, M_{P}$ and $Λ\sim m_{GUT}$ where $Λ$ can be seen as the strong coupling scale of a given non-abelian gauge group. However, the latest observational constraints put natural inflation in some tension with data. We show here that a non-minimal coupling to gravity $γ^2(ϕ) R$, that respects the symmetry $ϕ\rightarrow ϕ+2 πf$ and has a simple form, proportional to the potential, can improve the agreement with cosmological data. Moreover, in certain cases, satisfactory agreement with the Planck 2018 TT, TE, EE and low P data can be achieved even for a periodicity scale of approximately $M_p$.

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Ricardo Z. Ferreira, Alessio Notari, Guillem Simeon. 2018-11-16. Natural Inflation with a periodic non-minimal coupling. https://doi.org/10.1088/1475-7516%2F2018%2F11%2F021

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