Simple Predictions from Multifield Inflationary Models

Richard Easther, Jonathan Frazer, Hiranya V. Peiris, and Layne C. Price
Phys. Rev. Lett. 112, 161302 – Published 22 April 2014

Abstract

We explore whether multifield inflationary models make unambiguous predictions for fundamental cosmological observables. Focusing on N-quadratic inflation, we numerically evaluate the full perturbation equations for models with 2, 3, and O(100) fields, using several distinct methods for specifying the initial values of the background fields. All scenarios are highly predictive, with the probability distribution functions of the cosmological observables becoming more sharply peaked as N increases. For N=100 fields, 95% of our Monte Carlo samples fall in the ranges ns(0.9455,0.9534), α(9.741,7.047)×104, r(0.1445,0.1449), and riso(0.02137,3.510)×103 for the spectral index, running, tensor-to-scalar ratio, and isocurvature-to-adiabatic ratio, respectively. The expected amplitude of isocurvature perturbations grows with N, raising the possibility that many-field models may be sensitive to postinflationary physics and suggesting new avenues for testing these scenarios.

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  • Received 5 February 2014

DOI:https://doi.org/10.1103/PhysRevLett.112.161302

© 2014 American Physical Society

Authors & Affiliations

Richard Easther1,*, Jonathan Frazer2,3,†, Hiranya V. Peiris2,‡, and Layne C. Price1,§

  • 1Department of Physics, University of Auckland, Private Bag 92019, Auckland, New Zealand
  • 2Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
  • 3Department of Theoretical Physics, University of the Basque Country UPV/EHU, 48040 Bilbao, Spain

  • *r.easther@auckland.ac.nz
  • j.frazer@ucl.ac.uk
  • h.peiris@ucl.ac.uk
  • §lpri691@aucklanduni.ac.nz

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Issue

Vol. 112, Iss. 16 — 25 April 2014

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