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One might wonder how the captain of a large ship can navigate through the ocean with just a turn of the steering wheel. The answer lies in the concept of two parallel forces that are equal in magnitude and opposite sense, creating a couple moment.
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Multifield inflation after Planck: the case for nonminimal couplings.

David I Kaiser1, Evangelos I Sfakianakis1

  • 1Department of Physics and Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

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|February 4, 2014
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Multifield inflation models with nonminimal couplings align with Planck data, accurately predicting key cosmological parameters. These models also explain low cosmic microwave background power by amplifying isocurvature perturbations, distinguishing future observations.

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Area of Science:

  • Cosmology
  • Theoretical Physics

Background:

  • Cosmic Microwave Background (CMB) observations provide crucial data for understanding the early universe.
  • Inflationary cosmology is the leading paradigm for explaining the universe's initial conditions.

Purpose of the Study:

  • To investigate multifield inflation models with nonminimal couplings.
  • To assess the agreement of these models with recent Planck satellite data.
  • To explore the potential of these models to explain observed CMB anomalies.

Main Methods:

  • Analysis of multifield inflation models incorporating nonminimal couplings.
  • Comparison of model predictions with observational data from the Planck mission.
  • Investigation of the evolution of cosmological perturbations within these models.

Main Results:

  • Multifield models with nonminimal couplings show excellent agreement with Planck results.
  • These models predict primordial spectral index, its running, tensor-to-scalar ratio, and non-Gaussianities within favored observational regions.
  • The models successfully amplify isocurvature perturbations, potentially explaining low CMB power at low multipoles.

Conclusions:

  • Multifield inflation with nonminimal couplings is a viable framework consistent with current cosmological observations.
  • These models offer an explanation for the observed low power in the CMB power spectrum.
  • Future measurements of primordial isocurvature perturbations will be key to distinguishing between viable inflationary models.