179 citations · 1.2k across the 42 of their papers we have counts for
20 papers · 1 filter
Cosmological Perturbation Theory in Metric-Affine Gravity
Katsuki Aoki, Sebastian Bahamonde, Jorge Gigante Valcarcel +1
We formulate cosmological perturbation theory around the spatially curved FLRW background in the context of metric-affine gauge theory of gravity which includes torsion and nonmetr…
Coupled vector Gauss-Bonnet theories and hairy black holes
Katsuki Aoki, Shinji Tsujikawa
We study vector-tensor theories in which a 4-dimensional vector field is coupled to a vector quantity , which is expressed in terms of and a metric tensor $…
Some disquisitions on cosmological 2-form dualities
Katsuki Aoki, Jose Beltrán Jiménez, David Figueruelo
In this work we study different aspect of self-interacting 2-form fields with special emphasis in their cosmological applications. We provide the explicit construction of how massl…
Highly compact Proca stars with quartic self-interactions
Katsuki Aoki, Masato Minamitsuji
We study self-gravitating bound states of a complex vector field, known as Proca stars, with a new type of quartic-order self-interaction which does not exist in the case of either…
Spin-2 dark matter from anisotropic Universe in bigravity
Yusuke Manita, Katsuki Aoki, Tomohiro Fujita +1
Bigravity is one of the natural extensions of general relativity and contains an additional massive spin-2 field which can be a good candidate for dark matter. To discuss the produ…
Resolving the pathologies of self-interacting Proca fields: A case study of Proca stars
Katsuki Aoki, Masato Minamitsuji
It has been argued that a self-interacting massive vector field is pathological due to a dynamical formation of a singular effective metric of the vector field, which is the onset…
Shift-symmetric multi-Galileon
Katsuki Aoki, Yusuke Manita, Shinji Mukohyama
A Poincarè invariant, local scalar field theory in which the Lagrangian and the equation of motion contain only up to second-order derivatives of the fields is called generalized G…
Non-uniqueness of massless transverse-traceless graviton
Katsuki Aoki, Francesco Di Filippo, Shinji Mukohyama
We study a theory of minimally modified gravity called cuscuton/VCDM that propagates only two gravitational degrees of freedom. Despite being apparently different from general rela…
Inflationary gravitational waves in consistent Einstein-Gauss-Bonnet gravity
Katsuki Aoki, Mohammad Ali Gorji, Shuntaro Mizuno +1
We study the slow-roll single field inflation in the context of the consistent Einstein-Gauss-Bonnet gravity that was recently proposed in \cite{Aoki:2020lig}. In addition…
Cosmology and gravitational waves in consistent Einstein-Gauss-Bonnet gravity
Katsuki Aoki, Mohammad Ali Gorji, Shinji Mukohyama
In a very recent paper [1], we have proposed a novel -dimensional gravitational theory with two dynamical degrees of freedom, which serves as a consistent realization of …
A consistent theory of Einstein-Gauss-Bonnet gravity
Katsuki Aoki, Mohammad Ali Gorji, Shinji Mukohyama
We investigate the limit of the -dimensional Einstein-Gauss-Bonnet gravity, where the limit is taken with kept fixed and is the original…
Metric-affine Gravity and Inflation
Keigo Shimada, Katsuki Aoki, Kei-ichi Maeda
We classify the metric-affine theories of gravitation, in which the metric and the connections are treated as independent variables, by use of several constraints on the connection…
Phenomenology in type-I minimally modified gravity
Katsuki Aoki, Antonio De Felice, Chunshan Lin +2
We study cosmology in a class of minimally modified gravity (MMG) with two local gravitational degrees of freedom. We classify modified gravity theories into type-I and type-II: th…
Galileon and generalized Galileon with projective invariance in a metric-affine formalism
Katsuki Aoki, Keigo Shimada
We study scalar-tensor theories respecting the projective invariance in the metric-affine formalism. The metric-affine formalism is a formulation of gravitational theories such tha…
Novel matter coupling in general relativity via canonical transformation
Katsuki Aoki, Chunshan Lin, Shinji Mukohyama
We study canonical transformations of general relativity (GR) to provide a novel matter coupling to gravity. Although the transformed theory is equivalent to GR in vacuum, the equi…
Massive Graviton Geons
Katsuki Aoki, Kei-ichi Maeda, Yosuke Misonoh +1
We find vacuum solutions such that massive gravitons are confined in a local spacetime region by their gravitational energy in asymptotically flat spacetimes in the context of the…
Massive graviton dark matter with environment dependent mass: A natural explanation of the dark matter-baryon ratio
Katsuki Aoki, Shinji Mukohyama
We propose a scenario that can naturally explain the observed dark matter-baryon ratio in the context of bimetric theory with a chameleon field. We introduce two additional gravita…
Relativistic stars in bigravity theory
Katsuki Aoki, Kei-ichi Maeda, Makoto Tanabe
Assuming static and spherically symmetric spacetimes in the ghost-free bigravity theory, we find a relativistic star solution, which is very close to that in general relativity. Th…
Dark matter in ghost-free bigravity theory: From a galaxy scale to the universe
Katsuki Aoki, Kei-ichi Maeda
We study the origin of dark matter based on the ghost-free bigravity theory with twin matter fluids. The present cosmic acceleration can be explained by the existence of graviton m…
Cosmology in ghost-free bigravity theory with twin matter fluids: The origin of "dark matter"
Katsuki Aoki, Kei-ichi Maeda
We study dynamics of Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime based on the ghost-free bigravity theory. Assuming the coupling parameters guaranteeing the existence of d…