Initial conditions for inflation

Abstract

Within the $\alpha$-attractors framework we investigate scalar potentials with the same pole as the one featured in the kinetic term. We show that, in field space, this leads to directions without a plateau. Using this, we present a proposal, which manages to overcome the initial conditions problem of inflation with a plateau. An earlier period of proto-inflation, beginning at Planck scale, accounts for the Universe expansion and arranges the required initial conditions for inflation on the plateau to commence. We show that, if proto-inflation is power-law, it does not suffer from a sub-Planckian eternal inflationary stage, which would otherwise be a problem. A simple model realisation is constructed in the context of $\alpha$-attractors, which can both generate the inflationary plateau and the exponential slopes around it, necessary for the two inflation stages. Our mechanism allows to assume chaotic initial conditions at the Planck scale for proto-inflation, it is generic and it is shown to work without fine-tuning.

14 pages, 1 figure

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• Breathing Comoving Hubble: Initial Condition and Eternity in view of the trans-Planckian Censorship Conjecture
• On CMB B-modes and the Onset of Inflation
• Hill-climbing dark inflation
• Time-reversed Stochastic Inflation