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Title: Constraints on the tensor-to-scalar ratio for non-power-law models

Recent cosmological observations hint at a deviation from the simple power-law form of the primordial spectrum of curvature perturbations. In this paper we show that in the presence of a tensor component, a turn-over in the initial spectrum is preferred by current observations, and hence non-power-law models ought to be considered. For instance, for a power-law parameterisation with both a tensor component and running parameter, current data show a preference for a negative running at more than 2.5σ C.L. As a consequence of this deviation from a power-law, constraints on the tensor-to-scalar ratio r are slightly broader. We also present constraints on the inflationary parameters for a model-independent reconstruction and the Lasenby and Doran (LD) model. In particular, the constraints on the tensor-to-scalar ratio from the LD model are: r{sub LD} = 0.11±0.024. In addition to current data, we show expected constraints from Planck-like and CMB-Pol sensitivity experiments by using Markov-Chain-Monte-Carlo sampling chains. For all the models, we have included the Bayesian Evidence to perform a model selection analysis. The Bayes factor, using current observations, shows a strong preference for the LD model over the standard power-law parameterisation, and provides an insight into the accuracy of differentiating models through futuremore » surveys.« less
Authors:
;  [1] ;  [2] ;  [3]
  1. Kavli Institute for Cosmology, Madingley Road,Cambridge CB3 0HA (United Kingdom)
  2. Department of Physics and Astronomy, University of British Columbia, Agricultural Road, Vancouver BC V6T 1Z1 (Canada)
  3. Astrophysics Group, Cavendish Laboratory, JJ Thomson Avenue, Cambridge, CB3 0HE (United Kingdom)
Publication Date:
OSTI Identifier:
22282692
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2013; Journal Issue: 08; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMOLOGY; ENERGY SPECTRA; INFLATIONARY UNIVERSE; INFLATONS; LIMITING VALUES; MARKOV PROCESS; MONTE CARLO METHOD; PERTURBATION THEORY; SCALARS; SENSITIVITY; TENSORS