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Vainshtein screening in a cosmological background in the most general second-order scalar-tensor theory
Rampei Kimura, Tsutomu Kobayashi, Kazuhiro Yamamoto
A generic second-order scalar-tensor theory contains a nonlinear derivative self-interaction of the scalar degree of freedom à la Galileon models, which allows for the Vainshte…
Observational Constraints on Kinetic Gravity Braiding from the Integrated Sachs-Wolfe Effect
Rampei Kimura, Tsutomu Kobayashi, Kazuhiro Yamamoto
The cross-correlation between the integrated Sachs-Wolfe (ISW) effect and the large scale structure (LSS) is a powerful tool to constrain dark energy and alternative theories of gr…
Primordial non-Gaussianities of gravitational waves in the most general single-field inflation model
Xian Gao, Tsutomu Kobayashi, Masahide Yamaguchi +1
We completely clarify the feature of primordial non-Gaussianities of tensor perturbations in generalized G-inflation, i.e., the most general single-field inflation model with secon…
Effective gravitational couplings for cosmological perturbations in the most general scalar-tensor theories with second-order field equations
Antonio De Felice, Tsutomu Kobayashi, Shinji Tsujikawa
In the Horndeski's most general scalar-tensor theories the equations of scalar density perturbations are derived in the presence of non-relativistic matter minimally coupled to gra…
Generalized G-inflation: Inflation with the most general second-order field equations
Tsutomu Kobayashi, Masahide Yamaguchi, Jun'ichi Yokoyama
We study generalized Galileons as a framework to develop the most general single-field inflation models ever, Generalized G-inflation, containing yet further generalization of G-in…
Oscillating Bianchi IX Universe in Horava-Lifshitz Gravity
Yosuke Misonoh, Kei-ichi Maeda, Tsutomu Kobayashi
We study a vacuum Bianchi IX universe in the context of Hořava-Lifshitz (HL) gravity. In particular, we focus on the classical dynamics of the universe and analyze how anisotropy c…