Non-minimally coupled curvaton

Abstract

We investigate two-field inflationary models in which scalar cosmological pertubations are generated via a spectator field nonminimally coupled to gravity, with the particular emphasis on curvaton scenarios. The principal advantage of these models is in the possibility to tune the spectator spectral index via the nonminimal coupling. Our models naturally yield red spectrum of the adiabatic perturbation demanded by observations. We study how the nonminimal coupling affects the spectrum of the curvature perturbation generated in the curvaton scenarios. In particular we find that for small, negative nonminimal couplings the spectral index gets a contribution that is negative and linear in the nonminimal coupling. Since in this way the curvature spectrum becomes redder, some of curvaton scenarios can be saved, which would otherwise be ruled out. In the power law inflation we find that a large nonminimal coupling is excluded since it gives the principal slow roll parameter that is of the order of unity. Finally, we point out that nonminimal coupling can affect the postinflationary growth of the spectator perturbation, and in this way the effectiveness of the curvaton mechanism.

41 pages, 4 figures. Accepted for publication in JCAP

References in corpus (7)

• The Unity of Cosmological Attractors
• Perturbations in generalized multi-field inflation
• Primordial Bispectrum from Multifield Inflation with Nonminimal Couplings
• Gravitational wave production from preheating: parameter dependence
• Runnings in the Curvaton
• Curvaton Decay by Resonant Production of the Standard Model Higgs
• Violation of slow-roll in non-minimal inflation

Cited by in corpus (12)

• The recent gravitational wave observation by pulsar timing arrays and primordial black holes: the importance of non-gaussianities
• Primordial black holes in the curvaton model: possible connections to pulsar timing arrays and dark matter
• Curbing PBHs with PTAs
• Constraints on primordial black holes from LIGO-Virgo-KAGRA O3 events
• The primordial black hole from running curvaton
• The Irrelevance of Primordial Black Hole Clustering in the LVK mass range
• Complexity of non-trivial sound speed in inflation
• Nonminimally Assisted Inflation: A General Analysis
• Mimetic Curvaton
• Double inflation via non-minimally coupled spectator
• Inflationary power spectrum from the Lanczos algorithm
• Krylov complexity of thermal state in early universe