39 citations · 150 across the 6 of their papers we have counts for
6 papers
Resonant Signatures of Heavy Scalar Fields in the Cosmic Microwave Background
Ryo Saito, Masahiro Nakashima, Yu-ichi Takamizu +1
We investigate the possibility that a heavy scalar field, whose mass exceeds the Hubble scale during inflation, could leave non-negligible signatures in the Cosmic Microwave Backgr…
The Music of the Aetherwave - B-mode Polarization in Einstein-Aether Theory
Masahiro Nakashima, Tsutomu Kobayashi
We study how the dynamical vector degree of freedom in modified gravity affects the CMB B-mode polarization in terms of the Einstein-aether theory. In this theory, vector perturbat…
CMB Polarization in Einstein-Aether Theory
Masahiro Nakashima, Tsutomu Kobayashi
We study the impact of modifying the vector sector of gravity on the CMB polarization. We employ the Einstein-aether theory as a concrete example. The Einstein-aether theory admits…
The effect of varying sound velocity on primordial curvature perturbations
Masahiro Nakashima, Ryo Saito, Yu-ichi Takamizu +1
We study the effects of sudden change in the sound velocity on primordial curvature perturbation spectrum in inflationary cosmology, assuming that the background evolution satisfie…
Constraining the time variation of the coupling constants from cosmic microwave background: effect of Λ_{QCD}
Masahiro Nakashima, Kazuhide Ichikawa, Ryo Nagata +1
We investigate constraints on the time variation of the fine structure constant between the recombination epoch and the present epoch, Δα/α\equiv (α_{rec} - α_{now})/α_{now}, from…
Constraints on the time variation of the fine structure constant by the 5-year WMAP data
Masahiro Nakashima, Ryo Nagata, Jun'ichi Yokoyama
The constraints on the time variation of the fine structure constant at recombination epoch relative to its present value, $Δα/α\equiv (α_{\mathrm{rec}} - α_{\mathrm{now}})/α_{\mat…