Ohta, Nobuyoshi, Torii, Takashi
We study black hole solutions in the Einstein gravity with Gauss-Bonnet term, the dilaton and a positive "cosmological constant" in various dimensions. Physically meaningful black holes with a...
Ohta, Nobuyoshi, Torii, Takashi
We study black hole solutions in the Einstein-Gauss-Bonnet gravity with the dilaton and a negative ``cosmological constant''. We derive the field equations for the static spherically symmetric...
Guo, Zong-Kuan, Ohta, Nobuyoshi, Torii, Takashi
We study asymptotically AdS topological black hole solutions with k=0 (plane symmetric) in the Einstein gravity with Gauss-Bonnet term, the dilaton and a "cosmological constant" in various...
$N+1$ formalism in Einstein-Gauss-Bonnet gravity (2008)
Torii, Takashi, Shinkai, Hisa-aki
Towards the investigation of the full dynamics in higher-dimensional and/or stringy gravitational model, we present the basic equations of the Einstein-Gauss-Bonnet gravity theory. We show...
Guo, Zong-Kuan, Ohta, Nobuyoshi, Torii, Takashi
We study spherically symmetric, asymptotically flat black hole solutions in the low-energy effective heterotic string theory, which is the Einstein gravity with Gauss-Bonnet term and the dilaton, in...
NAS Switch: A Novel CIFS Server Virtualization (2008)
Wataru Katsurashima, Satoshi Yamakawa, Takashi Torii, Jun Ishikawa, Yoshihide Kikuchi
This paper proposes a CIFS Server virtualization method which requires no proprietary software or hardware for clients or NAS units. The method is implemented as an in-band network application...
Non-Abelian Black Holes in Brans-Dicke Theory (2007)
We find a black hole solution with non-Abelian field in Brans-Dicke theory. It is an extension of non-Abelian black hole in general relativity. We discuss two non-Abelian fields: "SU(2)"...
We discuss black holes in an effective theory derived from a superstring model, which includes a dilaton field, a gauge field and the Gauss-Bonnet term. Assuming U(1) or SU(2) symmetry for the gauge...
Spacetime structure of static solutions in Gauss-Bonnet gravity: charged case (2005)
We have studied spacetime structures of static solutions in the $n$-dimensional Einstein-Gauss-Bonnet-Maxwell-$\Lambda$ system. Especially we focus on effects of the Maxwell charge. We assume that...
Spacetime structure of static solutions in Gauss-Bonnet gravity: neutral case (2005)
We study the spacetime structures of the static solutions in the $n$-dimensional Einstein-Gauss-Bonnet-$\Lambda$ system systematically. We assume the Gauss-Bonnet coefficient $\alpha$ is...
Novel Cauchy-horizon instability (2005)
Maeda, Hideki, Torii, Takashi, Harada, Tomohiro
The evolution of weak discontinuity is investigated on horizons in the $n$-dimensional static solutions in the Einstein-Maxwell-scalar-$\Lambda$ system, including the Reissner-Nordstr\"om-(anti) de...
Horizon Instability: a Local Analysis (2004)
Maeda, Hideki; Advanced Research Institute For Science And Engineering, Was; Hideki@gravity.phys.waseda.ac.jp, Torii, Takashi; Graduate School Of Science, Waseda University, Tokyo; Torii@gravity.phys.waseda.ac.jp, Harada, Tomohiro; School Of Mathematical Sciences, Queen Mary, University Of London; T.Harada@qmul.ac.uk
The evolution of weak discontinuity is investigated on horizons in the n-dimensional static solutions in the Einstein-Maxwell-scalar-\Lambda system, including the Reissner-Nordstr"om-(anti) de Sitter...
Regular and Black Hole Skyrmions with Axisymmetry (2004)
Shiiki, Noriko, Sawado, Nobuyuki, Torii, Takashi, Maeda, Kei-ichi
It has been known that a B=2 skyrmion is axially symmetric. We consider the Skyrme model coupled to gravity and obtain static axially symmetric regular and black hole solutions numerically. Computing...
D-braneworld cosmology II: Higher order corrections (2003)
Uesugi, Tomoko, Shiromizu, Tetsuya, Torii, Takashi, Takahashi, Keitaro
We investigate braneworld cosmology based on the D-brane initiated in our previous paper. The brane is described by a Born-Infeld action and the gauge field is contained. The higher order corrections...
Covariant Gravitational Equations on Brane World with Gauss-Bonnet term (2003)
Maeda, Kei-ichi, Torii, Takashi
We present the covariant gravitational equations to describe a four-dimensional brane world in the case with the Gauss-Bonnet term in a bulk spacetime, assuming that gravity is confined on the $Z_2$...
Cosmological constant and gravitational theory on D-brane (2003)
Shiromizu, Tetsuya, Koyama, Kazuya, Torii, Takashi
In a toy model we derive the gravitational equation on a self-gravitating curved D-brane. The effective theory on the brane is drastically changed from the ordinal Einstein equation. The net...
Perturbations of global monopoles as a black hole's hair (2003)
Watabe, Hiroshi, Torii, Takashi
We study the stability of a spherically symmetric black hole with a global monopole hair. Asymptotically the spacetime is flat but has a deficit solid angle which depends on the vacuum expectation...
Can we live on a D-brane? -- Effective theory on a self-gravitating D-brane -- (2003)
Shiromizu, Tetsuya, Koyama, Kazuya, Onda, Sumitada, Torii, Takashi
We consider a D-brane coupled with gravity in type IIB supergravity on S^5 and derive the effective theory on the D-brane in two different ways, that is, holographic and geometrical projection...
Effective Gravitational Equations on Brane World with Induced Gravity (2003)
Maeda, Kei-ichi, Mizuno, Shuntaro, Torii, Takashi
We present the effective equations to describe the four-dimensional gravity of a brane world, assuming that a five-dimensional bulk spacetime satisfies the Einstein equations and gravity is confined...
Shiromizu, Tetsuya, Torii, Takashi, Uesugi, Tomoko
We discuss D-braneworld cosmology, that is, the brane is described by the Born-Infeld action. Compared with the usual Randall-Sundrum braneworld cosmology where the brane action is the Nambu-Goto...
One more mechanism of electric charge non-conservation (2002)
Dolgov, Alexander D., Maeda, Hideki, Torii, Takashi
If photon mass is not exactly zero, though arbitrary small, electric charge would not be conserved in interaction of charged particles with black holes. Manifestations of such mechanism of electric...
Cosmological constant, dilaton field and Freund-Rubin compactification (2002)
Torii, Takashi, Shiromizu, Tetsuya
We discuss the Freund-Rubin compactification with cosmological constant and the dilaton field, and examine the stability of the spacetimes at the low energy. The Minkowski or de Sitter spacetime can...
Particle velocity in noncommutative space-time (2002)
Tamaki, Takashi, Harada, Tomohiro, Miyamoto, Umpei, Torii, Takashi
We investigate a particle velocity in the $\kappa$-Minkowski space-time, which is one of the realization of a noncommutative space-time. We emphasize that arrival time analyses by high-energy...
Polar Perturbations of Self-gravitating Supermassive Global Monopoles (2002)
Watabe, Hiroshi, Torii, Takashi
Spontaneous global symmetry breaking of O(3) scalar field gives rise to point-like topological defects, global monopoles. By taking into account self-gravity,the qualitative feature of the global...
Have we already detected astrophysical symptoms of space-time noncommutativity ? (2001)
Tamaki, Takashi, Harada, Tomohiro, Miyamoto, Umpei, Torii, Takashi
We discuss astrophysical implications of $\kappa$-Minkowski space-time, in which there appears space-time noncommutativity. We first derive a velocity formula for particles based on the motion of a...
Gravitational energy, dS/CFT correspondence and cosmic no-hair (2001)
Shiromizu, Tetsuya, Ida, Daisuke, Torii, Takashi
The gravitational energy is examined in asymptotically de Sitter space-times. The positivity will be shown for certain cases. The de Sitter/CFT(dS/CFT) correspondence recently proposed and cosmic...
Stability of $AdS_p x S^n x S^{q-n}$ Compactifications (2001)
Shiromizu, Tetsuya, Ida, Daisuke, Ochiai, Hirotaka, Torii, Takashi
We examine the stability of ${\rm AdS}_p \times {\rm S}^n \times {\rm S}^{q-n}$. The initial data constructed by De Wolfe et al \cite{Gary} has been carefully analyised and we have confirmed that...
Internal structure of Skyrme black hole (2001)
Tamaki, Takashi, Maeda, Kei-ichi, Torii, Takashi
We consider the internal structure of the Skyrme black hole under a static and spherically symmetric ansatz. $@u8(Be concentrate on solutions with the node number one and with the "winding" number...
Brane-World and Holography (2001)
Shiromizu, Tetsuya, Torii, Takashi, Ida, Daisuke
We consider the brane-world in the holographic point of view. Bearing the realistic models in mind, the bulk massless scalar field is introduced. First of all, we find the constraint on the coupling...
Vacuum energy of CP(1) solitons (2001)
Moss, Ian G, Shiiki, Noriko, Torii, Takashi
The vacuum energy of two CP(1) solitons on a torus is computed numerically. A numerical technique for zeta-function regularisation is proposed to remove the divergences of the vacuum energy. After...
Dyonic BIon black hole in string inspired model (2001)
Tamaki, Takashi, Torii, Takashi
We construct static and spherically symmetric particle-like and black hole solutions with magnetic and/or electric charge in the Einstein-Born-Infeld-dilaton-axion system, which is a generalization...
Maeda, Kengo, Torii, Takashi, Narita, Makoto, Yahikozawa, Shigeaki
We investigate how much a first-quantized charged bosonic test string gets excited after crossing a shock wave generated by a charged particle with mass $\tilde{M}$ and charge $\tilde{Q}$. On the...
Gravitating BIon and BIon black hole with dilaton (2000)
Tamaki, Takashi, Torii, Takashi
We construct static and spherically symmetric particle-like and black hole solutions with magnetic or electric charge in the Einstein-Born-Infeld-dilaton system, which is a generalization of the...
Asymptotic singular behavior of Gowdy spacetimes in string theory (2000)
Narita, Makoto, Torii, Takashi, Maeda, Kengo
We study $T^{3}$ Gowdy spacetimes in the Einstein-Maxwell-dilaton-axion system and show by the Fuchsian algorithm that they have in general asymptotically velocity-term dominated singularities. The...
Violation of the cosmic no hair conjecture in Einstein-Maxwell-dilaton system (1999)
Maeda, Kengo, Torii, Takashi, Narita, Makoto
The cosmic no hair conjecture is tested in the spherically symmetric Einstein-Maxwell-dilaton~(EMD) system with a positive cosmological constant $\Lambda$. Firstly, we analytically show that once...
String excitation inside generic black holes (1999)
Maeda, Kengo, Torii, Takashi, Narita, Makoto
We calculate how much a first-quantized string is excited after crossing the inner horizon of charged Vaidya solutions, as a simple model of generic black holes. To quantize a string suitably, we...
Gravitating monopole and its black hole solution in Brans-Dicke Theory (1999)
Tamaki, Takashi, Torii, Takashi, Maeda, Kei-ichi
We find a self-gravitating monopole and its black hole solution in Brans-Dicke theory. We mainly discuss the properties of these solutions in the Einstein frame and compare the solutions with those...
Do naked singularities generically occur in generalized theories of gravity? (1998)
Maeda, Kengo, Torii, Takashi, Narita, Makoto
A new mechanism for causing naked singularities is found in an effective superstring theory. We investigate the gravitational collapse in a spherically symmetric Einstein-Maxwell-dilaton system in...
Non-Abelian Black Holes in Brans-Dicke Theory (1997)
Tamaki, Takashi, Torii, Takashi, Maeda, Kei-ichi
We find a black hole solution with non-Abelian field in Brans-Dicke theory. It is an extension of non-Abelian black hole in general relativity. We discuss two non-Abelian fields: "SU(2)" Yang-Mills...
Dilatonic Black Holes with Gauss-Bonnet Term (1996)
Torii, Takashi, Yajima, Hiroki, Maeda, Kei-ichi
We discuss black holes in an effective theory derived from a superstring model, which includes a dilaton field, a gauge field and the Gauss-Bonnet term. Assuming U(1) or SU(2) symmetry for the gauge...
Cosmic Colored Black Holes (1995)
Torii, Takashi, Maeda, Kei-ichi, Tachizawa, Takashi
We present spherically symmetric static solutions (a particle-like solution and a black hole solution) in the Einstein-Yang-Mills system with a cosmological constant.Although their gravitational...
Non-Abelian Black Holes and Catastrophe Theory I : Neutral Type (1994)
Torii, Takashi, Maeda, Kei-ichi, Tachizawa, Takashi
We re-analyze the globally neutral non-Abelian black holes and present a unified picture, classifying them into two types; Type I (black holes with massless non-Abelian field) and Type II (black...