179 citations · 1.2k across the 42 of their papers we have counts for
15 papers · 1 filter
Effective Field Theory of Black Hole Perturbations in Vector-Tensor Gravity
Katsuki Aoki, Mohammad Ali Gorji, Shinji Mukohyama +2
We formulate the effective field theory (EFT) of vector-tensor gravity for perturbations around an arbitrary background with a vector profile, which can be applied…
Unitarity and unstable-particle scattering amplitudes
Katsuki Aoki
Unitarity is the fundamental property of the S-matrix while its usage for a scattering of unstable particles has been subtle as unstable particles do not appear in the asymptotic s…
Effective Field Theory of Gravitating Continuum: Solids, Fluids, and Aether Unified
Katsuki Aoki, Mohammad Ali Gorji, Shinji Mukohyama +1
We investigate the relativistic effective field theory (EFT) describing a non-dissipative gravitating continuum. In addition to ordinary continua, namely solids and fluids, we find…
The Effective Field Theory of Vector-Tensor Theories
Katsuki Aoki, Mohammad Ali Gorji, Shinji Mukohyama +1
We investigate a systematic formulation of vector-tensor theories based on the effective field theory (EFT) approach. The input of our EFT is that the spacetime symmetry is spontan…
Positivity vs. Lorentz-violation: an explicit example
Katsuki Aoki, Shinji Mukohyama, Ryo Namba
We show how a class of multi-field scalar-field theories in a Lorentz-breaking background imposes consistency conditions on its effective theory of a single field and provides an e…
Is the Standard Model in the Swampland? Consistency Requirements from Gravitational Scattering
Katsuki Aoki, Tran Quang Loc, Toshifumi Noumi +1
We study compatibility of the Standard Model of particle physics and General Relativity by means of gravitational positivity bounds, which provide a necessary condition for a low-e…
Non-linearly ghost-free higher curvature gravity
Katsuki Aoki
We find unitary and local theories of higher curvature gravity in the vielbein formalism, known as the Poincaré gauge theory by utilizing the equivalence to the ghost-free massive…
Gravitational positivity bounds
Junsei Tokuda, Katsuki Aoki, Shin'ichi Hirano
We study the validity of positivity bounds in the presence of a massless graviton, assuming the Regge behavior of the amplitude. Under this assumption, the problematic -channel…
Consistent inflationary cosmology from quadratic gravity with dynamical torsion
Katsuki Aoki, Shinji Mukohyama
The idea of gauge theories of gravity predicts that there should exist not only the massless graviton but also massive particles carrying the gravitational force. We study the cosm…
Ghostfree quadratic curvature theories with massive spin-2 and spin-0 particles
Katsuki Aoki, Shinji Mukohyama
We consider generic derivative corrections to the Einstein gravity and find new classes of theories without ghost around the Minkowski background by means of an extension of the sp…
Scalar-metric-affine theories: Can we get ghost-free theories from symmetry?
Katsuki Aoki, Keigo Shimada
We reveal the existence of a certain hidden symmetry in general ghost-free scalar-tensor theories which can only be seen when generalizing the geometry of the spacetime from Rieman…
Condensate of Massive Graviton and Dark Matter
Katsuki Aoki, Kei-ichi Maeda
We study coherently oscillating massive gravitons in the ghost-free bigravity theory. This coherent field can be interpreted as a condensate of the massive gravitons. We first defi…
Vainshtein mechanism in massive gravity nonlinear sigma models
Katsuki Aoki, Shuntaro Mizuno
We study the stability of the Vainshtein screening solution of the massive/bi-gravity based on the massive nonlinear sigma model as the effective action inside the Vainshtein radiu…
Massive gravitons as dark matter and gravitational waves
Katsuki Aoki, Shinji Mukohyama
We consider the possibility that the massive graviton is a viable candidate of dark matter in the context of bimetric gravity. We first derive the energy-momentum tensor of the mas…
Stability of the Early Universe in Bigravity Theory
Katsuki Aoki, Kei-ichi Maeda, Ryo Namba
We study the stability of a spherically symmetric perturbation around the flat Friedmann-Lematre-Robertson-Walker spacetime in the ghost-free bigravity theory, retaining non…