Constraints on a mixed inflaton and curvaton scenario for the generation of the curvature perturbation

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Title: Constraints on a mixed inflaton and curvaton scenario for the generation of the curvature perturbation
Authors: Lazarides, G
Ruiz de Austri, R
Trotta, R
Item Type: Journal Article
Abstract: We consider a supersymmetric grand unified model which naturally solves the strong CP and mu problems via a Peccei-Quinn symmetry and leads to the standard realization of hybrid inflation. We show that the Peccei-Quinn field of this model can act as curvaton. In contrast to the standard curvaton hypothesis, both the inflaton and the curvaton contribute to the total curvature perturbation. The model predicts an isocurvature perturbation too which has mixed correlation with the adiabatic one. The cold dark matter of the universe is mostly constituted by axions plus a small amount of lightest sparticles. The predictions of the model are confronted with the Wilkinson microwave anisotropy probe and other cosmic microwave background radiation data. We analyze two representative choices of parameters and derive bounds on the curvaton contribution to the adiabatic perturbation. We find that, for the choice which provides the best fitting of the data, the curvaton contribution to the adiabatic amplitude must be smaller than about 67% (at 95% confidence level). The best-fit power spectra are dominated by the adiabatic part of the inflaton contribution. We use Bayesian model comparison to show that this choice of parameters is disfavored with respect to the pure inflaton scale-invariant case with odds of 50 to 1. For the second choice of parameters, the adiabatic mode is dominated by the curvaton, but this choice is strongly disfavored relative to the pure inflaton scale-invariant case (with odds of 10^7 to 1). We conclude that in the present framework the perturbations must be dominated by the adiabatic component from the inflaton.
Issue Date: 22-Dec-2004
Date of Acceptance: 29-Sep-2004
ISSN: 1550-7998
Publisher: APS Physics
Journal / Book Title: Physical Review D
Volume: 70
Issue: 12
Copyright Statement: © 2004 The American Physical Society
Keywords: hep-ph
Nuclear & Particles Physics
0201 Astronomical And Space Sciences
0202 Atomic, Molecular, Nuclear, Particle And Plasma Physics
0206 Quantum Physics
Publication Status: Published
Article Number: 123527
Appears in Collections:Physics
Faculty of Natural Sciences

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