Multi-field Cuscuton Cosmology
arXiv:2207.06720 · doi:10.1088/1475-7516/2023/01/022
Abstract
In this paper, we first introduce a multi-field setup of Cuscuton gravity in a curved field space manifold. Then, we show that this model allows for a regular bouncing cosmology and it does not lead to ghosts or other instabilities at the level of perturbations. More precisely, by decomposing the scalar fields perturbations into the tangential and normal components with respect to the background field space trajectory, the entropy mode perpendicular to the background trajectory is healthy which directly depends on the signature of the field-space metric, whereas the adiabatic perturbation tangential to the background trajectory is frozen. In analogy with the standard Cuscuton theory equipped with an extra dynamical scalar field, the adiabatic field does not have its own dynamics, but it modifies the dynamics of other dynamical fields like entropy mode in our scenario. Finally, we perform a Hamiltonian analysis of our model in order to count the degrees of freedom propagated by dynamical fields.
arXiv comment19 pages, minor revisions, accepted by JCAP
References in corpus (46)
- Quantum Gravity at a Lifshitz Point
- The Dynamics of General Relativity
- The galileon as a local modification of gravity
- From k-essence to generalised Galileons
- Healthy theories beyond Horndeski
- Adiabatic and entropy perturbations from inflation
- Exploring gravitational theories beyond Horndeski
- k-Essence, superluminal propagation, causality and emergent geometry
- Null energy condition and superluminal propagation
- G-Bounce
- Cuscuton: A Causal Field Theory with an Infinite Speed of Sound
- The Null Energy Condition and its violation
- Perturbations in generalized multi-field inflation
- Effective theories of single field inflation when heavy fields matter
- Generic instabilities of non-singular cosmologies in Horndeski theory: a no-go theorem
- Classically stable non-singular cosmological bounces
- On the importance of heavy fields during inflation
- Generalized Galileons: instabilities of bouncing and Genesis cosmologies and modified Genesis
- Inflation and primordial non-Gaussianities of "generalized Galileons"
- DBI Galileons in the Einstein Frame: Local Gravity and Cosmology
- Fully stable cosmological solutions with a non-singular classical bounce
- Cuscuton Cosmology: Dark Energy meets Modified Gravity
- Cuscuton and low energy limit of Horava-Lifshitz gravity
- Subluminal Galilean Genesis
- Extended Cuscuton: Formulation
- A Closed Formula for the Riemann Normal Coordinate Expansion
- Hidden Negative Energies in Strongly Accelerated Universes
- Unbraiding the Bounce: Superluminality around the Corner
- When Matter Matters
- The inflationary bispectrum with curved field-space
- A theory of type-II minimally modified gravity
- Multi-field inflation and cosmological perturbations
- Cumulative effects in inflation with ultra-light entropy modes
- Cuscuton Bounce
- Hamiltonian analysis of the cuscuton
- Cuscuton gravity as a classically stable limiting curvature theory
- Caustics for Spherical Waves
- Revisiting the cuscuton as a Lorentz-violating gravity theory
- VCDM and Cuscuton
- Theory of Cosmological Perturbations with Cuscuton
- Spectrum of Cuscuton Bounce
- Dressed Power-law Inflation with Cuscuton
- Cuscuton Inflation
- Path integral for multi-field inflation
- Magnon Inflation: Slow Roll with Steep Potentials
- Multi-field Mimetic Gravity