2007/08/01 by Hooshyar Assadullahi, Jussi Valiviita, J. Väliviita +1 · 3 citations
Physics and Astronomy · #Advanced Differential Geometry Research #Black Holes and Theoretical Physics #Cosmic microwave background #Cosmology and Gravitation Theories #Inflation (cosmology) #Non-Gaussianity #Nonlinear system #Particle physics #Perturbation (astronomy) #Perturbation theory (quantum mechanics) #Physics #Quantum electrodynamics #Quantum mechanics #Scalar (mathematics) #Spectral density #Statistics #astro-ph #hep-ph
paper · pdf · doi:10.1103/physrevd.76.103003
published as Phys.Rev.D76:103003,2007 · 20 pages, 5 figures
arxiv created 2007/08/01 · openalex publication_date 2007/11/13 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We study a model where two scalar fields, that are subdominant during inflation, decay into radiation some time after inflation has ended but before primordial nucleosynthesis. Perturbations of these two curvaton fields can be responsible for the primordial curvature perturbation. We write down the full nonlinear equations that relate the primordial perturbation to the curvaton perturbations on large scales, calculate the power spectrum of the primordial perturbation, and finally go to second order to find the nonlinearity parameter, fNL. We find large positive values of fNL if the energy densities of the curvatons are subdominant when they decay, as in the single curvaton case. But we also find a large fNL even if the curvatons dominate the total energy density in the case when the inhomogeneous radiation produced by the first curvaton decay is diluted by the decay of a second nearly homogeneous curvaton. The minimum value min(fNL)=\ensuremath-5/4 which we find is the same as in the single-curvaton case.