25 citations · 66 across the 6 of their papers we have counts for
6 papers
Imprints of primordial gravitational waves with non-Bunch-Davies initial states on CMB bispectra
Shingo Akama, Hiroaki W. H. Tahara
It has been shown that both scalar and tensor modes with non-Bunch-Davies initial states can enhance the amplitudes of the primordial bispectra compared to those with the Bunch-Dav…
Nanohertz gravitational waves from NEC violation in the early universe
Hiroaki W. H. Tahara, Tsutomu Kobayashi
We study nanohertz gravitational waves relevant to pulsar timing array experiments from quantum fluctuations in the early universe with null energy condition (NEC) violation. The N…
A new mechanism for freezing extra dimensions with higher-order curvature terms
Hiroaki W. H. Tahara, Tsutomu Kobayashi, Jun'ichi Yokoyama
We construct a model of higher dimensional cosmology in which extra dimensions are frozen by virtue of the cubic-order Lovelock gravity throughout the cosmic history from inflation…
Kompaneets equation for neutrinos: Application to neutrino heating in supernova explosions
Yudai Suwa, Hiroaki W. H. Tahara, Eiichiro Komatsu
We derive a `Kompaneets equation' for neutrinos, which describes how the distribution function of neutrinos interacting with matter deviates from a Fermi-Dirac distribution with ze…
Self-anisotropizing inflationary universe in Horndeski theory and beyond
Hiroaki W. H. Tahara, Sakine Nishi, Tsutomu Kobayashi +1
As opposed to Wald's cosmic no-hair theorem in general relativity, it is shown that the Horndeski theory (and its generalization) admits anisotropic inflationary attractors if the…
CMB B-mode auto-bispectrum produced by primordial gravitational waves
Hiroaki W. H. Tahara, Jun'ichi Yokoyama
Gravitational waves from inflation induce polarization patterns in the cosmic microwave background (CMB). It is known that there are only two types of non-Gaussianities of the grav…