Bimetric varying speed of light theories and primordial fluctuations
arXiv:0807.1689 · doi:10.1103/PhysRevD.79.043525
Abstract
We exhibit a varying speed of light (VSL) theory that implements the recently proposed decaying speed of sound mechanism for generating density fluctuations. We avail ourselves of bimetric VSL theories, where the speed of gravity differs from that of light. We first show that a Dirac-Born-Infeld (DBI) type of -essence has the necessary speed of sound profile to produce (near) scale-invariant fluctuations. We then examine the map between bimetric and -essence models: typically the bi-scalar connecting the two metrics is a -essence field in one of them. Remarkably, the DBI model is found to perturbatively represent the minimal bimetric model, where the bi-scalar is Klein-Gordon in the matter frame. But the full non-perturbative bimetric structure is even simpler: the bi-scalar dynamics should be simply driven by a cosmological constant in the matter frame, balanced by an opposite cosmological constant in the gravity frame. Thus the problem of structure formation receives an elegant and universal solution within bimetric VSL theories, which are known to also solve the flatness and entropy problems and evade a plethora of causality concerns.
References in corpus (22)
- Causality, Analyticity and an IR Obstruction to UV Completion
- k-Essence, superluminal propagation, causality and emergent geometry
- Producing a Scale-Invariant Spectrum of Perturbations in a Hagedorn Phase of String Cosmology
- Cuscuton: A Causal Field Theory with an Infinite Speed of Sound
- Primordial perturbations and non-Gaussianities in DBI and general multi-field inflation
- Primordial fluctuations and non-Gaussianities in multi-field DBI inflation
- On causality and superluminal behavior in classical field theories. Applications to k-essence theories and MOND-like theories of gravity
- String Gas Cosmology and Structure Formation
- Enhancing the tensor-to-scalar ratio in simple inflation
- Non-perturbative Gravity, Hagedorn Bounce & CMB
- Cuscuton Cosmology: Dark Energy meets Modified Gravity
- No-go theorem for k-essence dark energy
- Speedy sound and cosmic structure
- Quantum modes in DBI inflation: exact solutions and constraints from vacuum selection
- Reconstructing a general inflationary action
- More on the Spectrum of Perturbations in String Gas Cosmology
- Thermal fluctuations in loop cosmology
- Near Scale Invariance with Modified Dispersion Relations
- Holography and the scale-invariance of density fluctuations
- Seeding of Primordial Perturbations During a Decelerated Expansion
- Comments on "Note on varying speed of light theories"
- Observing the temperature of the Big Bang through large scale structure
Cited by in corpus (53)
- Imperfect Dark Energy from Kinetic Gravity Braiding
- Primordial Black Holes from Sound Speed Resonance during Inflation
- An Infinite Set of Ward Identities for Adiabatic Modes in Cosmology
- Primordial Perturbation in Horava-Lifshitz Cosmology
- Cosmological disformal invariance
- DBI Realizations of the Pseudo-Conformal Universe and Galilean Genesis Scenarios
- Primordial perturbation with a modified dispersion relation
- Multifractional theories: an unconventional review
- Multi-scale gravity and cosmology
- Rainbow gravity and scale-invariant fluctuations
- Cosmological Tests of the Disformal Coupling to Radiation
- Dimensional reduction in the sky
- Dark D-brane Cosmology
- Quantum gravity and gravitational-wave astronomy
- Tachyacoustic Cosmology: An Alternative to Inflation
- Variable Speed of Light Cosmology, Primordial Fluctuations and Gravitational Waves
- Non-Gaussianity in single field models without slow-roll
- Intermediate inflation from rainbow gravity
- Bimetric structure formation: non-Gaussian predictions
- Geometric scalar theory of gravity
- The critical geometry of a thermal big bang
- Cyclic Inflation
- Disformal invariance of Maxwell's field equations
- Varying electric charge in multiscale spacetimes
- Quantum Field Theory in a Multi-Metric Background
- New class of generalized coupling theories
- Braneworld solutions from scalar field in bimetric theory
- Observational constraints on dual intermediate inflation
- Inflationary Krylov complexity
- Supercomputers against strong coupling in gravity with curvature and torsion
- Vacuum Cherenkov radiation and bremsstrahlung from disformal couplings
- Strong Coupling Problem with Time-Varying Sound Speed
- Einstein-Proca theory from the Einstein-Cartan formulation
- Nonlinear Hamiltonian analysis of new quadratic torsion theories Part I. Cases with curvature-free constraints
- Bayesian evidence and predictivity of the inflationary paradigm
- Noncommutative gravity with self-dual variables
- Primordial fluctuations without scalar fields
- Chiral symmetry breaking as a geometrical process
- The phenomenology of squeezing and its status in non-inflationary theories
- Minimal exponential measure model in the post-Newtonian limit
- Cosmological complexity of the modified dispersion relation
- Gravity, Cartan geometry, and idealized waywisers
- Void or Dark Energy?
- An introduction to the physics of Cartan gravity
- Ether and Relativity
- Attractor Solutions in Tachyacoustic Cosmology
- Non-Gaussian signatures of Tachyacoustic Cosmology
- Some coordinate transformations relevant to refractive indices
- Squeezing of scalar and tensor primordial perturbations generated by modified dispersion relations
- Primordial standing waves
- Bimetric Models of Gravity and Cosmology in the Early Universe
- Bimetric Gravity, Variable Speed of Light Cosmology and Planck2013
- Non-Gaussian Signatures of a Thermal Big Bang