Speaker: José Fonseca
Location: Queen Mary, University of London
We consider a scenario where both the curvaton and the inflaton perturbations contribute to the primordial power spectrum. We will review perturbations from inflation and the curvaton model. We will then study mixed inflaton-curvaton perturbations and how they get transferred to the radiation fluid. Firstly we will consider the curvaton domination of the power spectrum and how non-Gaussianity of the primordial density perturbation and the amplitude of gravitational waves from inflation can be used to determine parameters of the curvaton scenario for the origin of structure. We show that in the simplest quadratic model, where the curvaton evolves as a free scalar field, measurement of the bispectrum relative to the power spectrum, fNL, and the tensor-to-scalar ratio can determine both the expectation value of the curvaton field during inflation and its dimensionless decay rate relative to the curvaton mass. Afterwards we will study the parameter space to identify the regimes in which curvaton dominates the primordial power spectrum and the one in which inflaton contributes significantly to the power spectrum. We will then use a similar approach (as the curvaton limit one) to study the parameter space in the mixed scenario and to study how it changes with the first slow roll parameter.