83 citations · 400 across the 18 of their papers we have counts for
3 papers · 1 filter
Primordial non-Gaussianities of scalar and tensor perturbations in general bounce cosmology: Evading the no-go theorem
Shingo Akama, Shin'ichi Hirano, Tsutomu Kobayashi
It has been pointed out that matter bounce cosmology driven by a k-essence field cannot satisfy simultaneously the observational bounds on the tensor-to-scalar ratio and non-Gaussi…
On the screening mechanism in DHOST theories evading gravitational wave constraints
Shin'ichi Hirano, Tsutomu Kobayashi, Daisuke Yamauchi
We consider a subclass of degenerate higher-order scalar-tensor (DHOST) theories in which gravitational waves propagate at the speed of light and do not decay into scalar fluctuati…
Constraining DHOST theories with linear growth of matter density fluctuations
Shin'ichi Hirano, Tsutomu Kobayashi, Daisuke Yamauchi +1
We investigate the potential of cosmological observations, such as galaxy surveys, for constraining degenerate higher-order scalar-tensor (DHOST) theories, focusing in particular o…