Preheating after multifield inflation with nonminimal couplings. II. Resonance structure

Journal Article · 26 January 2018 · Physical Review. D.

DOI: https://doi.org/10.1103/physrevd.97.023527 · OSTI ID:1505819

DeCross, Matthew P. ^[1]; Kaiser, David I. ^[1]; Prabhu, Anirudh ^[1]; Prescod-Weinstein, Chanda ^[2]; Sfakianakis, Evangelos I. ^[3]

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1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Physics
2. Univ. of Washington, Seattle, WA (United States). Dept. of Physics
3. Univ. of Illinois, Urbana, IL (United States). Dept. of Physics

This is the second in a series of papers on preheating in inflationary models comprised of multiple scalar fields coupled nonminimally to gravity. We work in the rigid-spacetime approximation and consider field trajectories within the single-field attractor, which is a generic feature of these models. We construct the Floquet charts to find regions of parameter space in which particle production is efficient for both the adiabatic and isocurvature modes, and analyze the resonance structure using analytic and semianalytic techniques. Particle production in the adiabatic direction is characterized by the existence of an asymptotic scaling solution at large values of the nonminimal couplings, $${{\xi}}_{I}{\gg}1$$, in which the dominant instability band arises in the long-wavelength limit, for comoving wave numbers $$k{\rightarrow}0$$. However, the large-$${{\xi}}_{I}$$ regime is not reached until $${{\xi}}_{I}{\ge}\mathcal{O}(100)$$. In the intermediate regime, with $${{\xi}}_{I}{\sim}\mathcal{O}(1-10)$$, the resonance structure depends strongly on wave number and couplings. The resonance structure for isocurvature perturbations is distinct and more complicated than its adiabatic counterpart. An intermediate regime, for $${{\xi}}_{I}{\sim}\mathcal{O}(1-10)$$, is again evident. For large values of $${{\xi}}_{I}$$, the Floquet chart consists of densely spaced, nearly parallel instability bands, suggesting a very efficient preheating behavior. The increased efficiency arises from features of the nontrivial field-space manifold in the Einstein frame, which itself arises from the fields’ nonminimal couplings in the Jordan frame, and has no analog in models with minimal couplings. Quantitatively, the approach to the large-$${{\xi}}_{I}$$ asymptotic solution for isocurvature modes is slower than in the case of the adiabatic modes.

• Research Organization: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP); USDOE
• Grant/Contract Number: SC0012567
• OSTI ID: 1505819
• Alternate ID(s): OSTI ID: 1418192
• Journal Information: Physical Review. D., Vol. 97, Issue 2; ISSN 2470-0010
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English