201 citations · 1.9k across the 28 of their papers we have counts for
12 papers · 1 filter
Limits on Isocurvature Perturbations from Non-Gaussianity in WMAP Temperature Anisotropies
Chiaki Hikage, Kazuya Koyama, Takahiko Matsubara +2
We study the effect of primordial isocurvature perturbations on non-Gaussian properties of CMB temperature anisotropies. We consider generic forms of the non-linearity of isocurvat…
Signature of Primordial Non-Gaussianity on Matter Power Spectrum
Atsushi Taruya, Kazuya Koyama, Takahiko Matsubara
Employing the perturbative treatment of gravitational clustering, we discuss possible effects of primordial non-Gaussianity on the matter power spectrum. As gravitational clusterin…
Detectability of a phantom-like braneworld model with the integrated Sachs-Wolfe effect
Tommaso Giannantonio, Yong-Seon Song, Kazuya Koyama
We study a braneworld model in which a phantom-like behaviour occurs with only cold dark matter and a cosmological constant, due to a large distance modification of gravity. With t…
Consistency test of general relativity from large scale structure of the Universe
Yong-Seon Song, Kazuya Koyama
We construct a consistency test of General Relativity (GR) on cosmological scales. This test enables us to distinguish between the two alternatives to explain the late-time acceler…
Cosmological perturbations in the DGP braneworld: numeric solution
Antonio Cardoso, Kazuya Koyama, Sanjeev S. Seahra +1
We solve for the behaviour of cosmological perturbations in the Dvali-Gabadadze-Porrati (DGP) braneworld model using a new numerical method. Unlike some other approaches in the lit…
Brane-world inflation: slow-roll corrections to the spectral index
Kazuya Koyama, Andrew Mennim, David Wands
We quantify the slow-roll corrections to primordial density perturbations arising from inflation driven by a four-dimensional scalar field with a monomial potential in a five-dimen…