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AT1 - Extended Theories of Gravity and Quantum Cosmology

Speaker

Motohashi, Hayato

Coauthors

Motohashi, Hayato; Starobinsky, Alexei A.; Yokoyama, Jun'ichi

Talk Title

Constant-roll inflation

Abstract

We propose a phenomenological class of inflationary models in which the assumption of inflaton slow-roll is replaced by more general, constant-roll condition. We derive general exact solution for the inflaton potential and dynamics, and show that there exists parameter region that satisfies the latest observational constraint on the scalar spectral index and the tensor-to-scalar ratio. We also consider its generalization to the case of f(R) gravity, for which we provide a simple constant-roll condition defined in the original, Jordan frame. The f(R) constant roll inflation also allows us to obtain exact solutions for the scalaron potential in the Einstein frame, the function f(R) in the parametric form and inflationary dynamics, which satisfies the observationally constraint. ----- References: Motohashi, Starobinsky, Yokoyama, JCAP 1509, 018 (2015), [arXiv:1411.5021]. Motohashi, Starobinsky, Europhys. Lett. 117, 39001 (2017), [arXiv:1702.05847]. Motohashi, Starobinsky, Eur.Phys.J. C77, 538 (2017), [arXiv:1704.08188].

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