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The role of fluctuation-dissipation dynamics in setting the initial conditions for inflation

Lookup NU author(s): Professor Ian MossORCiD



We study the problem of initial conditions for slow-roll inflation along a plateau- like scalar potential within the framework of fluctuation-dissipation dynamics. We consider, in particular, that inflation was preceded by a radiation-dominated epoch where the inflaton is coupled to light degrees of freedom and may reach a near-equilibrium state. We show that the homogeneous field component can be sufficiently localized at the origin to trigger a period of slow-roll if the interactions between the inflaton and the thermal degrees of freedom are sufficiently strong and argue that this does not necessarily spoil the flatness of the potential at the quantum level. We further conclude that the inflaton can still be held at the origin after its potential begins to dominate the energy balance, leading to a period of thermal inflation. This then suppresses the effects of nonlinear interactions between the homogeneous and inhomogeneous field modes that could prevent the former from entering a slow-roll regime. Finally, we discuss the possibility of an early period of chaotic inflation, at large field values, followed by a first stage of reheating and subsequently by a second inflationary epoch along the plateau about the origin. This scenario could prevent an early overclosure of the Universe, at the same time yielding a low tensor-to-scalar ratio in agreement with observations.

Publication metadata

Author(s): Bastero-Gil M, Berera A, Brandenberger R, Moss IG, Ramose RO, Rosa JG

Publication type: Article

Publication status: Published

Journal: Journal of Cosmology and Astroparticle Physics

Year: 2018

Volume: 1

Online publication date: 02/01/2018

Acceptance date: 15/12/2017

Date deposited: 26/02/2018

ISSN (electronic): 1475-7516

Publisher: IOP Publishing Ltd


DOI: 10.1088/1475-7516/2018/01/002


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