Tachyonic Preheating in Plateau Inflation

Abstract

Plateau inflation is an experimentally consistent framework in which the scale of inflation can be kept relatively low. Close to the edge of the plateau, scalar perturbations are subject to a strong tachyonic instability. Tachyonic preheating is realized when, after inflation, the oscillating inflaton repeatedly re-enters the plateau. We develop the analytic theory of this process and expand the linear approach by including backreaction between the coherent background and growing perturbations. For a family of plateau models, the analytic predictions are confronted with numerical estimates. Our analysis shows that the inflaton fragments in a fraction of an $e$-fold in all examples supporting tachyonic preheating, generalizing the results of previous similar studies. In these scenarios, the scalar-to-tensor ratio is tiny, $r<10^{-7}$.

32 pages, 7 figures. v2: Updated to match published version. Added references

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Cited by in corpus (6)

• Implications of stochastic effects for primordial black hole production in ultra-slow-roll inflation
• Reheating in Models with Non-minimal Coupling in metric and Palatini formalisms
• Preheating in Palatini Higgs inflation on the lattice
• The Linear Regime of Tachyonic Preheating
• Dissipation of oscillating scalar backgrounds in an FLRW universe
• General Analytical Conditions for Inflaton Fragmentation: Quick and Easy Tests for its Occurrence