Quantifying the 'naturalness' of the curvaton model

Lerner, Rose; Melville, Scott

Preprint/Internal Report

DESY-2014-02303

Quantifying the 'naturalness' of the curvaton model

Lerner, R. (Corresponding Author)DESY* ; Melville, S.

2014

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Report No.: DESY-14-015; arXiv:1402.3176

Abstract: We investigate the probability of obtaining an observable curvature perturbation, using as an example the minimal curvaton-higgs (MCH) model. We determine ``probably observable'' and ``probably excluded'' regions of parameter space assuming generic initial conditions and applying a stochastic approach for the curvaton's evolution during inflation. Inflation is assumed to last longer than the N(obs) simeq 55 observable e-folds, and the total number of e-folds of inflation determines the particular ranges of parameters that are probable. For the MCH model, these ``probably observable'' regions always lie within the range 8 × 10(4) GeV ≤ m(σ) ≤ 2 × 10(7) GeV, where m(σ) is the curvaton mass, and the Hubble scale at horizon exit is chosen as H(*) = 10(10) GeV. Because the ``probably observable'' region depends on the total duration of inflation, information on parameters in the Lagrangian from particle physics and from precision CMB observations can therefore provide information about the total duration of inflation, not just the last N(obs) e-folds. This method could also be applied to any model that contains additional scalar fields to determine the probability that these scalar fields contribute to the curvature perturbation.

Keyword(s): inflation (LCSH) ; initial conditions and eternal universe (LCSH) ; non-gaussianity (LCSH) ; curvature: perturbation ; field theory: scalar ; curvaton: mass ; inflation ; cosmic background radiation ; boundary condition ; stochastic ; horizon