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Non-Gaussian curvature spikes from chaotic billiards in inflation preheating.

Physical review letters·2009
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Related Experiment Video

Updated: Jul 2, 2026

Setting Limits on Supersymmetry Using Simplified Models
07:46

Setting Limits on Supersymmetry Using Simplified Models

Published on: November 15, 2013

Singularity problem with f(R) models for dark energy.

Andrei V Frolov1

  • 1Department of Physics, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada. frolov@sfu.ca

Physical Review Letters
|September 4, 2008
PubMed
Summary
This summary is machine-generated.

Many modified gravity f(R) models face a nonlinear curvature singularity problem. This issue, invisible in linear analysis, impacts the viability of infrared f(R) theories when matter is present.

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Area of Science:

  • Cosmology
  • General Relativity
  • Modified Gravity Theories

Background:

  • f(R) theories are proposed modifications to Einstein's theory of gravity.
  • These theories aim to explain cosmic acceleration without dark energy.
  • Infrared (IR) modifications are particularly relevant for cosmological scales.

Purpose of the Study:

  • To identify and analyze a nonlinear curvature singularity problem in f(R) gravity models.
  • To investigate the implications of this singularity for the viability of these models.
  • To highlight the limitations of linearized analyses in detecting such issues.

Main Methods:

  • Nonlinear analysis of f(R) gravity models.
  • Investigation of the behavior of the effective scalar degree of freedom.
  • Examination of the impact of matter coupling on the scalar field dynamics.

Main Results:

  • A curvature singularity exists at a finite field value and energy level for the effective scalar degree of freedom in nonlinear f(R) models.
  • This singularity is accessible by field dynamics in the presence of matter.
  • Linearized analyses fail to reveal this singularity, only showing growing oscillatory modes.

Conclusions:

  • The nonlinear curvature singularity poses a significant challenge to many existing f(R) models.
  • The viability of numerous f(R) theories in the current literature requires reevaluation.
  • Future research should focus on developing f(R) models that avoid or mitigate this singularity.