Stringy bounces and gradient instabilities
arXiv:1612.00346 · doi:10.1103/PhysRevD.95.083506
Abstract
Bouncing solutions are obtained from a generally covariant action characterized by a potential which is a nonlocal functional of the dilaton field at two separated space-time points. Gradient instabilities are shown to arise in this context but they are argued to be nongeneric. After performing a gauge-invariant and frame-invariant derivation of the evolution equations of the fluctuations, a heuristic criterion for the avoidance of pathological instabilities is proposed and corroborated by a number of explicit examples that turn out to be compatible with a quasi-flat spectrum of curvature inhomogeneities for typical wavelengths larger than the Hubble radius.
25 pages; comments added and corrected typos; to appear in Phys. Rev. D
References in corpus (15)
- Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
- Three Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization Analysis
- Double Field Theory
- Effective Field Theory for Inflation
- The gauge algebra of double field theory and Courant brackets
- Generic instabilities of non-singular cosmologies in Horndeski theory: a no-go theorem
- The Effective Field Theory of nonsingular cosmology
- Generalized Galileons: instabilities of bouncing and Genesis cosmologies and modified Genesis
- Cosmological Perturbations Through a Non-Singular Ghost-Condensate/Galileon Bounce
- G-Bounce Inflation: Towards Nonsingular Inflation Cosmology with Galileon Field
- Cosmological Implications from O(D,D)
- Cosmological status of Lagrangian theory of density perturbations
- Evolution of linear perturbations through a bouncing world model: Is the near Harrison-Zel'dovich spectrum possible via a bounce?
- Uniform gradient expansions
- Bouncing Cosmologies
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