84 citations · 266 across the 7 of their papers we have counts for
6 papers
Nearly scale-invariant curvature modes from entropy perturbations during graceful exit
Anna Ijjas, Roman Kolevatov
In this Letter, we describe how a spectrum of entropic perturbations generated during a period of slow contraction can source a nearly scale-invariant spectrum of curvature perturb…
Sourcing curvature modes with entropy perturbations in non-singular bouncing cosmologies
Anna Ijjas, Roman Kolevatov
The observed temperature fluctuations in the cosmic microwave background can be traced back to primordial curvature modes that are sourced by adiabatic and/or entropic matter pertu…
Perturbations in generalized Galileon theories
R. Kolevatov, S. Mironov, V. Rubakov +2
We discuss the approaches by Deffayet et al. (DPSV) and Kobayashi et al. (KYY) to the analysis of linearized scalar perturbations about a spatially flat FLRW background in Horndesk…
Cosmological bounce and Genesis beyond Horndeski
R. Kolevatov, S. Mironov, N. Sukhov +1
We study a "classical" bouncing scenario in beyond Horndeski theory. We give an example of spatially flat bouncing solution that is non-singular and stable throughout the whole evo…
Cosmological bounces and Lorentzian wormholes in Galileon theories with an extra scalar field
R. Kolevatov, S. Mironov
We study whether it is possible to design a "classical" spatially flat bouncing cosmology or a static, spherically symmetric asymptotically flat Lorentzian wormhole in cubic Galile…
Superluminality in dilatationally invariant generalized Galileon theories
Roman Kolevatov
We consider small perturbations about homogeneous backgrounds in dilatationally-invariant Galileon models. The issues we address are stability (absence of ghosts and gradient insta…