Multifield Inflation after Planck: The Case for Nonminimal Couplings
  Multifield models of inflation with nonminimal couplings are in excellent
agreement with the recent results from {\it Planck}. Across a broad range of
couplings and initial conditions, such models evolve along an effectively
single-field attractor solution and predict values of the primordial spectral
index and its running, the tensor-to-scalar ratio, and non-Gaussianities
squarely in the observationally most-favored region. Such models also can
amplify isocurvature perturbations, which could account for the low power
recently observed in the CMB power spectrum at low multipoles. Future
measurements of primordial isocurvature perturbations and the tensor-to-scalar
ratio may serve to distinguish between the currently viable possibilities.
