24 citations · 47 across the 15 of their papers we have counts for
17 papers
Inverse design of scalar-tensor EFT from odd-parity effective potentials
Kazufumi Takahashi, Yuki Watanabe
We develop an inverse-design approach to the effective field theory (EFT) of perturbations in scalar-tensor gravity around static and spherically symmetric backgrounds with a timel…
Black Hole Quasinormal Mode Resonances and Reconnections in Coupled Systems
Leah Jenks, Hayato Motohashi, Kazufumi Takahashi +2
Black hole quasinormal modes (QNMs) provide a window into the underlying structure of black holes and the environments in which they arise. QNMs have particularly rich dynamics in…
Scalar quasinormal modes of rotating black holes in parity-violating gravity
Hiroaki W. H. Tahara, Hayato Motohashi, Kazufumi Takahashi +1
Recently, an exact rotating black hole solution in a parity-violating theory of gravity was obtained via a conformal transformation of the Kerr solution in general relativity, with…
Probing higher curvature gravity via ringdown with overtones
Keisuke Nakashi, Masashi Kimura, Hayato Motohashi +1
We investigate metric perturbations of a spherically symmetric black hole in higher curvature gravity. We show that higher curvature corrections deform the near-horizon region of t…
EFT of Dark Energy with Cosmic Chronometers: Reconstructing Background EFT Functions
Fumiya Okamatsu, Kazufumi Takahashi
The effective field theory (EFT) of dark energy provides a model-independent framework for studying cosmology within scalar-tensor theories. In this work, we explore how the time e…
Dynamical Tidal Response of Non-rotating Black Holes: Connecting the MST Formalism and Worldline EFT
Hajime Kobayashi, Shinji Mukohyama, Naritaka Oshita +2
The response of a black hole (BH) to tidal forces encodes key information about the underlying gravitational theory and affects the waveform of gravitational waves emitted during b…
Effective Field Theory of Perturbations on Arbitrary Black Hole Backgrounds with Spacelike Scalar Profile
Shinji Mukohyama, Emeric Seraille, Kazufumi Takahashi +1
We develop the effective field theory (EFT) of perturbations in the context of scalar-tensor theories with a spacelike scalar profile on arbitrary black hole backgrounds. Our const…
Resonance of black hole quasinormal modes in coupled systems
Takuya Takahashi, Hayato Motohashi, Kazufumi Takahashi
Black hole quasinormal modes (QNMs) can exhibit resonant excitations associated with avoided crossings in their complex frequency spectrum. Such resonance phenomena can serve as no…
Parametrized Tidal Dissipation Numbers of Non-rotating Black Holes
Hajime Kobayashi, Shinji Mukohyama, Naritaka Oshita +2
A set of tidal dissipation numbers (TDNs) quantifies the absorption of the tidal force exerted by a companion during an inspiralling phase of a binary compact object. This tidal di…
Quasinormal Modes from EFT of Black Hole Perturbations in Vector-Tensor Gravity
Shogo Tomizuka, Hajime Kobayashi, Naritaka Oshita +2
We study the dynamics of odd-parity perturbations on a static and spherically symmetric black hole background with a timelike vector field based on the effective field theory (EFT)…
Inverting no-hair theorems: How requiring General Relativity solutions restricts scalar-tensor theories
Hajime Kobayashi, Shinji Mukohyama, Johannes Noller +3
Black hole solutions in general scalar-tensor theories are known to permit hair, i.e. non-trivial scalar profiles and/or metric solutions different from the ones of General Relativ…
Spherical black hole perturbations in EFT of scalar-tensor gravity with timelike scalar profile
Shinji Mukohyama, Kazufumi Takahashi, Keitaro Tomikawa +1
We study linear even-parity perturbations of static and spherically symmetric black holes with a timelike scalar profile by use of the effective field theory (EFT) approach. For il…
Bridging Dark Energy and Black Holes with EFT: Frame Transformation and Gravitational Wave Speed
Shinji Mukohyama, Emeric Seraille, Kazufumi Takahashi +1
Typically, constraints on parameters of the effective field theory (EFT) of dark energy have been obtained in the Jordan frame, where matter fields are minimally coupled to gravity…
(In)stability of the black hole greybody factors and ringdowns against a small-bump correction
Naritaka Oshita, Kazufumi Takahashi, Shinji Mukohyama
Recently, it has been proposed that the black hole greybody factors can be important to model ringdown spectral amplitudes. We study the stability of greybody factors against a sma…
CMB spectrum in unified EFT of dark energy: scalar-tensor and vector-tensor theories
Katsuki Aoki, Mohammad Ali Gorji, Takashi Hiramatsu +3
We study the cosmic microwave background (CMB) radiation in the unified description of the effective field theory (EFT) of dark energy that accommodates both scalar-tensor and vect…
Tidal Love Numbers from EFT of Black Hole Perturbations with Timelike Scalar Profile
Chams Gharib Ali Barura, Hajime Kobayashi, Shinji Mukohyama +3
We study static tidal Love numbers (TLNs) of a static and spherically symmetric black hole for odd-parity metric perturbations. We describe black hole perturbations using the effec…
Black holes, multiple propagation speeds, and energy extraction
Vitor Cardoso, Shinji Mukohyama, Naritaka Oshita +1
The Standard Model of particle physics predicts the speed of light to be a universal speed of propagation of massless carriers. However, other possibilities exist -- including Lore…