4 papers
Scalar-scalar-tensor interaction in DHOST theories
S. Mironov, V. Volkova
We derive the general cubic action for perturbations about a cosmological background in the quadratic subclass of degenerate higher-order scalar-tensor (DHOST) theories, focusing o…
Non-singular cosmological scenarios in scalar-tensor theories and their stability: a review
S. Mironov, V. Volkova
This article gives a concise overview of the development and current status of studies on healthy models of the early Universe without an initial singularity, namely the cosmologic…
Linear stability of a time-dependent, spherically symmetric background in beyond Horndeski theory and the speed of gravity waves
S. Mironov, M. Sharov, V. Volkova
We address a dynamical, spherically symmetric background in beyond Horndeski theory and formulate a set of linear stability conditions for high energy perturbation modes above an a…
Complete stability for spherically symmetric backgrounds in beyond Horndeski theory
S. Mironov, V. Volkova
We consider a general static, spherically symmetric background in the quadratic beyond Horndeski theory and analyse the behaviour of linear perturbations in both parity odd and par…