3 papers
gr-qc2024
Slowly moving black holes in Lorentz-violating scalar-tensor gravity
Jin Saito, Tsutomu Kobayashi
A scalar field with a timelike gradient defines a preferred slicing. This occurs even in a non-cosmological setup in scalar-tensor theories such as khronometric theory. We study a…
gr-qc2024
PPN meets EFT of dark energy: Post-Newtonian approximation in higher-order scalar-tensor theories
Jin Saito, Zhibang Yao, Tsutomu Kobayashi
We study the post-Newtonian limit of higher-order scalar-tensor theories that are degenerate in the unitary gauge. They can be conveniently described by the effective field theory…
gr-qc2023
Black hole perturbations in spatially covariant gravity with just two tensorial degrees of freedom
Jin Saito, Tsutomu Kobayashi
We study linear perturbations around a static and spherically symmetric black hole solution in spatially covariant gravity with just two tensorial degrees of freedom. In this theor…