Nobuyoshi Ohta

Black Holes without Mass and Entropy in Lovelock Gravity (2009)

We present a class of exact analytic and static, spherically symmetric black hole solutions in the semi-classical Einstein equations with Weyl anomaly. The solutions have two branches, one is...

Global solutions for higher-dimensional stretched small black holes (2009)

We present a class of new black hole solutions in $D$-dimensional Lovelock gravity theory. The solutions have a form of direct product $\mathcal{M}^m \times \mathcal{H}^{n}$, where $D=m+n$,...

Chen, Chiang-Mei, Gal'tsov, Dmitri V., Ohta, Nobuyoshi, Orlov, Dmitry G.

Small black holes in heterotic string theory have vanishing horizon area at the supergravity level, but the horizon is stretched to the finite radius $AdS_2 \times S^{D-2}$ geometry once higher...

Horizon Thermodynamics and Gravitational Field Equations in Horava-Lifshitz Gravity (2009)

Generalized Misner-Sharp Energy in f(R) Gravity (2009)

We explore the relationship between the first law of thermodynamics and gravitational field equation at a static, spherically symmetric black hole horizon in Ho\v{r}ava-Lifshtiz theory with/without...

Cai, Rong-Gen, Cao, Li-Ming, Hu, Ya-Peng, Ohta, Nobuyoshi

We study generalized Misner-Sharp energy in $f(R)$ gravity in a spherically symmetric spacetime. We find that unlike the cases of Einstein gravity and Gauss-Bonnet gravity, the existence of the...

Black Hole Solutions in String Theory with Gauss-Bonnet Curvature Correction (2009)

Maeda, Kei-ichi, Ohta, Nobuyoshi, Sasagawa, Yukinori

We present the black hole solutions and analyse their properties in the superstring effective field theory with the Gauss-Bonnet curvature correction terms. We find qualitative differences in our...

Black Holes in the Dilatonic Einstein-Gauss-Bonnet Theory in Various Dimensions IV - Topological Black Holes with and without Cosmological Term (2009)

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...

Thermodynamics of Black Holes in Horava-Lifshitz Gravity (2009)

Topological Black Holes in Horava-Lifshitz Gravity (2009)

By using the canonical Hamiltonian method, we obtain the mass and entropy of the black holes with general dynamical coupling constant $\lambda$ in Ho\v{r} ava-Lifshitz Gravity. Regardless of whether...

Dynamics of intersecting brane systems -- Classification and their applications -- (2009)

We find topological (charged) black holes whose horizon has an arbitrary constant scalar curvature $2k$ in Ho\v{r}ava-Lifshitz theory. Without loss of generality, one may take $k=1,0$ and -1. The...

Maeda, Kei-ichi, Ohta, Nobuyoshi, Uzawa, Kunihito

We present dynamical intersecting brane solutions in higher-dimensional gravitational theory coupled to dilaton and several forms. Assuming the forms of metric, form fields, and dilaton field, we...

Supersymmetric Intersecting Branes in Time-dependent Backgrounds (2009)

Maeda, Kei-ichi, Ohta, Nobuyoshi, Tanabe, Makoto, Wakebe, Ryo

We construct a fairy general family of supersymmetric solutions in time- and space-dependent backgrounds in general supergravity theories. One class of the solutions are intersecting brane solutions...

Black Holes in the Dilatonic Einstein-Gauss-Bonnet Theory in Various Dimensions III -- Asymptotically AdS Black Holes with $k=\pm 1$ -- (2009)

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...

Shear Viscosity from Gauss-Bonnet Gravity with a Dilaton Coupling (2009)

Cai, Rong-Gen, Nie, Zhang-Yu, Ohta, Nobuyoshi, Sun, Ya-Wen

We calculate the shear viscosity of field theories with gravity duals of Gauss-Bonnet gravity with a non-trivial dilaton using AdS/CFT. We find that the dilaton filed has a non-trivial contribution...

Black Holes in the Dilatonic Einstein-Gauss-Bonnet Theory in Various Dimensions II -- Asymptotically AdS Topological Black Holes -- (2008)

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...

Black Holes in the Dilatonic Einstein-Gauss-Bonnet Theory in Various Dimensions I -- Asymptotically Flat Black Holes -- (2008)

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...

Generic estimates for magnetic fields generated during inflation including Dirac-Born-Infeld theories (2008)

Bamba, Kazuharu, Ohta, Nobuyoshi, Tsujikawa, Shinji

We estimate the strength of large-scale magnetic fields produced during inflation in the framework of Dirac-Born-Infeld (DBI) theories. This analysis is sufficiently general in the sense that it...

Cosmological Evolution of Dirac-Born-Infeld Field (2008)

Guo, Zong-Kuan, Ohta, Nobuyoshi

We investigate the cosmological evolution of the system of a Dirac-Born-Infeld field plus a perfect fluid. We analyze the existence and stability of scaling solutions for the AdS throat and the...

Entropy Function and Universality of Entropy-Area Relation for Small Black Holes (2007)

Cai, Rong-Gen, Chen, Chiang-Mei, Maeda, Kei-ichi, Ohta, Nobuyoshi, Pang, Da-Wei

We discuss the entropy-area relation for the small black holes with higher curvature corrections by using the entropy function formalism and field redefinition method. We show that the entropy...

Accelerating Cosmologies in the Einstein-Gauss-Bonnet Theory with Dilaton (2007)

Bamba, Kazuharu, Guo, Zong-Kuan, Ohta, Nobuyoshi

We study cosmological solutions in the low-energy effective heterotic string theory, which is the Einstein gravity with Gauss-Bonnet term and the dilaton. We show that the field equations are cast...

Deconfinement Transition of AdS/QCD at ${\cal O}(\alpha'^3)$ (2007)

Probing the Coupling between Dark Components of the Universe (2007)

We study the confinement/deconfinement phase transition of holographic AdS/QCD models by using Ricci flat $AdS_5$ black holes up to ${\cal O}(\alpha'^3)$, which corresponds to the $\lambda$ expansion...

Guo, Zong-Kuan, Ohta, Nobuyoshi, Tsujikawa, Shinji

We place observational constraints on a coupling between dark energy and dark matter by using 71 Type Ia supernovae (SNe Ia) from the first year of the five-year Supernova Legacy Survey (SNLS), the...

The D2 Susy Zoo (2006)

Bak, Dongsu, Ohta, Nobuyoshi, Townsend, Paul K.

We present new supersymmetric solutions of the Dirac-Born-Infeld equations for time-independent D2-branes, including a 1/2 supersymmetric `dyonic' D2-brane and various 1/4 supersymmetric...

Realizing Scale-invariant Density Perturbations in Low-energy Effective String Theory (2006)

Guo, Zong-Kuan, Ohta, Nobuyoshi, Tsujikawa, Shinji

We discuss the realization of inflation and resulting cosmological perturbations in the low-energy effective string theory. In order to obtain nearly scale-invariant spectra of density perturbations...

Supersymmetric Intersecting Branes in Time-dependent Backgrounds (2006)

Ohta, Nobuyoshi, Panigrahi, Kamal L.

We construct a family of supersymmetric solutions in time-dependent backgrounds in supergravity theories. One class of the solutions are intersecting brane solutions and another class are brane...

Addendum to "Hyperbolic Space Cosmologies" (2006)

Chen, Chiang-Mei, Ho, Pei-Ming, Neupane, Ishwaree P., Ohta, Nobuyoshi, Wang, John E.

In our earlier paper [JHEP 0310 (2003) 058], we considered higher dimensional cosmological models with hyperbolic spaces. In particular the eternal accelerating expansion was obtained by studying...

On the No-ghost Theorem in String Theory (2006)

Furuuchi, Kazuyuki, Ohta, Nobuyoshi

We give a simple proof of the no-ghost theorem in the critical bosonic string theory by using a similarity transformation.

Supersymmetric Rotating Black Hole in a Compactified Spacetime (2006)

Maeda, Kei-ichi, Ohta, Nobuyoshi, Tanabe, Makoto

We construct a supersymmetric rotating black hole with asymptotically flat four-dimensional spacetime times a circle, by superposing an infinite number of BMPV black hole solutions at the same...

Time-Dependent Supersymmetric Solutions in M-Theory and the Compactification-Decompactification Transition (2006)

Kodama, Hideo, Ohta, Nobuyoshi

We show that the diagonal light-like solution with 16 supersymmetries in eleven-dimensional supergravity derived in our previous paper (hep-th/0509173) can be generalised to non-diagonal solutions...

Black Holes in Pure Lovelock Gravities (2006)

Matrix String Description of Cosmic Singularities in a Class of Time-dependent Solutions (2006)

The Lovelock gravity is a fascinating extension of general relativity, whose action consists of the dimensionally extended Euler densities. Compared to other higher order derivative gravity theories,...

Ishino, Takayuki, Ohta, Nobuyoshi

A large class of time-dependent solutions with 1/2 supersymmetry were found previously. These solutions involve cosmic singularities at early time. In this paper, we study if matrix string...

Mass and Thermodynamics of Kaluza-Klein Black Holes with Squashed Horizons (2006)

Parametrizations of the Dark Energy Density and Scalar Potentials (2006)

Recently a five-dimensional Kaluza-Klein black hole solution with squashed horizon has been found in hep-th/0510094. The black hole spacetime is asymptotically locally flat and has a spatial infinity...

Guo, Zong-Kuan, Ohta, Nobuyoshi, Zhang, Yuan-Zhong

We develop a theoretical method of constructing the scalar (quintessence or phantom) potential directly from the dimensionless dark energy function X(z), the dark energy density in units of its...

Inflation from Superstring/M-Theory Compactification with Higher Order Corrections II -- Case of Quartic Weyl Terms -- (2006)

Akune, Kenta, Maeda, Kei-ichi, Ohta, Nobuyoshi

We present a detailed study of inflationary solutions in M-theory with higher order quantum corrections. We first exhaust all exact and asymptotic solutions of exponential and power-law expansions in...

Holography and D3-branes in Melvin Universes (2006)

A Note on Consistent Anomalies (2005)

Recently,in a paper hep-th/0511197, it was found that non-commutative super Yang-Mills (NCSYM) theory with space-dependent noncommutativity can be formulated as a decoupling limit of open strings...

Baulieu, Laurent, Laroche, Celine, Ohta, Nobuyoshi, Picco, Marco

Within a BRST formulation, we determine the expressions of the consistent anomaly for superstrings with extended worldsheet supersymmetries of rank N. We consider the O(N) superconformal algebras up...

M-theory Supertubes with Three and Four Charges (2005)

Bak, Dongsu, Kim, Kyungyu, Ohta, Nobuyoshi

Using the covariant M5-brane action, we construct configurations corresponding to supertubes with three and four charges. We derive the BPS equations and study the full structure of the solutions. In...

Time-dependent Solutions with Null Killing Spinor in M-theory and Superstrings (2005)

Ishino, Takayuki, Kodama, Hideo, Ohta, Nobuyoshi

Imposing the condition that there should be a null Killing spinor with all the metrics and background field strengths being functions of the light-cone coordinates, we find general 1/2 BPS solutions...

Intersecting Non-extreme p-Branes and Linear Dilaton Background (2005)

Chen, Chiang-Mei, Gal'tsov, Dmitri V., Ohta, Nobuyoshi

We construct the general static solution to the supergravity action containing gravity, the dilaton and a set of antisymmetric forms describing the intersecting branes delocalized in the relative...

Parametrization of Quintessence and Its Potential (2005)

Guo, Zong-Kuan, Ohta, Nobuyoshi, Zhang, Yuan-Zhong

We develop a theoretical method of constructing the quintessence potential directly from the effective equation of state function $w(z)$, which describes the properties of the dark energy. We apply...

Accelerating Cosmologies and Inflation from M/Superstring Theories (2004)

Inflation from Superstring/M Theory Compactification with Higher Order Corrections I (2004)

We review the recent developments in obtaining accelerating cosmologies and/or inflation from higher-dimensional gravitational theories, in particular superstring theories in ten dimensions and...

Maeda, Kei-ichi, Ohta, Nobuyoshi

We study time-dependent solutions in M and superstring theories with higher order corrections. We first present general field equations for theories of Lovelock type with stringy corrections in...

A Geometric Look on the Microstates of Supertubes (2004)

Bak, Dongsu, Hyakutake, Yoshifumi, Kim, Seok, Ohta, Nobuyoshi

We give a geometric interpretation of the entropy of the supertubes with fixed conserved charges and angular momenta in two different approaches using the DBI action and the supermembrane theory. By...

Inflation from M-Theory with Fourth-order Corrections and Large Extra Dimensions (2004)

Maeda, Kei-ichi, Ohta, Nobuyoshi

We study inflationary solutions in the M-theory. Including the fourth-order curvature correction terms, we find three generalized de Sitter solutions, in which our 3-space expands exponentially....

Phase Moduli Space of Supertubes (2004)

Bak, Dongsu, Hyakutake, Yoshifumi, Ohta, Nobuyoshi

We study possible deformations of BPS supertubes keeping their conserved charges fixed. We show that there is no flat direction to closed supertubes of circular cross section with uniform electric...

Complete Intersecting Non-Extreme p-Branes (2004)

Miao, Yan-Gang, Ohta, Nobuyoshi

We give general intersecting brane solutions without assuming any restriction on the metric in supergravity coupled to a dilaton and antisymmetric tensor fields in arbitrary dimensions $D$. The...

Dilatonic Repulsons and Confinement via the AdS/CFT Correspondence (2004)

Bak, Dongsu, Gutperle, Michael, Hirano, Shinji, Ohta, Nobuyoshi

We study a class of dilatonic deformations of asymptotically AdS_5 X S^5 geometry analytically and numerically. The spacetime is non-supersymmetric and suffers from a naked singularity. We propose...

Hyperbolic Space Cosmologies (2003)

Chen, Chiang-Mei, Ho, Pei-Ming, Neupane, Ishwaree P., Ohta, Nobuyoshi, Wang, John E.

We present a systematic study of accelerating cosmologies obtained from M/string theory compactifications of hyperbolic spaces with time-varying volume. A set of vacuum solutions where the internal...

Intersecting branes in pp-wave spacetime (2003)

Ohta, Nobuyoshi, Panigrahi, Kamal L.

We derive intersecting brane solutions in pp-wave spacetime by solving the supergravity field equations explicitly. The general intersection rules are presented. We also generalize the construction...

Uniqueness of M-theory PP-Wave Background with Extra Supersymmetries (2003)

Ohta, Nobuyoshi, Sakaguchi, Makoto

We examine Killing spinor equations of the general eleven-dimensional pp-wave backgrounds, which contain a scalar H(x^m,x^-) in the metric and a three-form \xi(x^m,x^-) in the flux. Considering...

A Study of Accelerating Cosmologies from Superstring/M theories (2003)

Accelerating Cosmologies from S-Branes (2003)

We study aspects of the accelerating cosmologies obtained from the compactification of vacuum solution and S2-branes of superstring/M theories. Parameter dependence of the resulting expansion of our...

Null-Brane Solutions in Supergravities (2003)

We point out that the recently proposed model of a flat 4-dimensional universe with accelerated expansion in string/M-theory is a special case of time-dependent solutions that the author found under...

Parent Actions, Dualities and New Weyl-invariant Actions of Bosonic p-branes (2003)

We find a new class of time-dependent brane solutions in supergravities in arbitrary dimensions $D$. These are general intersecting light-like branes (null-branes), and their superposition and...

Miao, Yan-Gang, Ohta, Nobuyoshi

By using the systematic approach of parent action method, we derive one Weyl-noninvariant and two Weyl-invariant actions of bosonic $p$-branes ($p\geq 2$) starting from the Nambu-Goto action, and...

Intersection Rules for S-Branes (2003)

NCOS and D-branes in Time-dependent Backgrounds (2002)

We give a model-independent derivation of general intersecting rules for spacelike branes (S-branes) in arbitrary dimensions $d$. This is achieved by directly solving bosonic field equations for...

Cai, Rong-Gen, Lu, Jian-Xin, Ohta, Nobuyoshi

We study noncommutative open string (NCOS) theories realized in string theory with time-dependent backgrounds. Starting from a noncommutative Yang-Mills theory (NCYM) with a constant space-space...

Supersymmetric Brane-Antibrane Systems: Matrix Model Description, Stability and Decoupling Limits (2002)

Bak, Dongsu, Ohta, Nobuyoshi, Sheikh-Jabbari, Mohammad M.

After reviewing the supertubes and super brane-antibrane systems in the context of matrix model, we look for more general higher-dimensional configurations. For D3-bar{D3}, we find a non-trivial...

Introduction to branes and M-theory for relativists and cosmologists (2002)

Supertubes and Supercurves from M-Ribbons (2002)

We review the recent developments in superstrings. We start with a brief summary of various consistent superstring theories and discuss T-duality which necessarily leads to the presence of D-branes....

Hyakutake, Yoshifumi, Ohta, Nobuyoshi

We construct 1/4 BPS configurations, `M-ribbons', in M-theory on T^2, which give the supertubes and supercurves in type IIA theory upon dimensional reduction. These M-ribbons are generalized so as to...

Moduli Space and Scattering of D0-Branes in Noncommutative Super Yang-Mills Theory (2001)

Hamanaka, Masashi, Imaizumi, Yasuyuki, Ohta, Nobuyoshi

We study the moduli space of the D0-brane system on Dp-branes realized in the noncommutative super Yang-Mills theory. By examining the fluctuations around the solitonic solutions generated by...

Supersymmetric D2 anti-D2 Strings (2001)

Bak, Dongsu, Ohta, Nobuyoshi

We consider the flat supersymmetric D2 and anti-D2 system, which follows from ordinary noncommutative D2 anti-D2 branes by turning on an appropriate worldvolume electric field describing dissolved...

Supersymmetry, Spectrum and Fate of D0-Dp Systems with B-field (2001)

Fujii, Akira, Imaizumi, Yasuyuki, Ohta, Nobuyoshi

It has been shown that D0-D$p$ $(p=2, 4, 6, 8)$ systems can be BPS in the presence of $B$-field even if they are not otherwise. We review the number of remaining supersymmetries, the open string...

Bekenstein Bound, Holography and Brane Cosmology in Charged Black Hole Backgrounds (2001)

Cai, Rong-Gen, Myung, Yun Soo, Ohta, Nobuyoshi

We obtain a Bekenstein entropy bound for the charged objects in arbitrary dimensions ($D\ge 4$) using the D-bound recently proposed by Bousso. With the help of thermodynamics of CFTs corresponding to...

OM Theory and V-duality (2001)

Cai, Rong-Gen, Ohta, Nobuyoshi, Lu, Jianxin, Roy, Shibaji, Wu, Yong-Shi

We show that the (M5, M2, M 2′, MW) bound state solution of eleven-dimensional supergravity recently constructed in hep-th/0009147 is related to the (M5, M2) bound state one by a finite Lorentz...

Noncommutative Gauge Dynamics from Brane Configurations with Background B field (2000)

Ohta, Nobuyoshi, Tomino, Dan

We study D=3 field theories on the D3-branes stretched between two NS5-branes with NS B-field background. The theory is a noncommutative gauge theory. The mirror symmetry and S-duality of the theory...

Lorentz Transformation and Light-Like Noncommutative SYM (2000)

(F1, D1, D3) Bound State, Its Scaling Limits and SL(2,Z) Duality (2000)

We show that combining the spatial noncommutative SYM limit and Lorentz transformation, one can obtain a well-behaved light-like noncommutative SYM limit. The light-like noncommutative SYM is...

Correspondence, Poincar'e Vacuum Stateand Greybody Factors in BTZ Black Holes (2000)

We discuss the properties of the bound state (F1, D1, D3) in IIB supergravity in three different scaling limits and the $SL(2,{\bf Z})$ transformation of the resulting theories. In the simple...

Noncommutative and Ordinary Super Yang-Mills on (D$(p-2)$, D$p$) Bound States (2000)

The greybody factors in BTZ black holes are evaluated from 2D CFT in the spirit of AdS3/CFT correspondence. The initial state of black holes in the usual calculation of greybody factors by effective...

M-brane interpolations and (2, 0) renormalization group flow (2000)

We study properties of (D$(p-2)$, D$p$) nonthreshold bound states ($2 \le p \le 6 $) in the dual gravity description. These bound states can be viewed as D$p$-branes with a nonzero NS $B$ field of...

Townsend, Paul K., Ohta, Nobuyoshi, Cai, Rong-Gen, Bergshoeff, Eric

We obtain the M5-M2-MW bound state solutions of 11-dimensional supergravity corresponding to the 1/2 supersymmetric vacua of the M5-brane equations with constant background fields. In the...

Surface counterterms and boundary stress-energy tensors for asymptotically non-anti-de Sitter spaces (1999)

On the Thermodynamics of Large N Noncommutative Super Yang-Mills Theory (1999)

For spaces which are not asymptotically anti-de Sitter where the asymptotic behavior is deformed by replacing the cosmological constant by a dilaton scalar potential, we show that it is possible to...

Spectrum of Maxwell-Chern-Simons Theory Realized on Type IIB Brane (1999)

We study the thermodynamics of the large N noncommutative super Yang-Mills theory in the strong 't Hooft coupling limit in the spirit of AdS/CFT correspondence. It has already been noticed that some...

Kitao, Takuhiro, Ohta, Nobuyoshi

We study the 3D field theory on one D3-brane stretched between (r,s) and (p,q)5-branes. The boundary conditions are determined from the analysis of NS5 and D5 charges of the two 5-branes. We carry...

Maxwell Chern-Simons Solitons from Type IIB String Theory (1999)

Lee, Bum-Hoon, Lee, Hyuk-jae, Ohta, Nobuyoshi, Yang, Hyun Seok

We study various three-dimensional supersymmetric Maxwell Chern-Simons solitons by using type IIB brane configurations. We give a systematic classification of soliton spectra such as topological BPS...

Spacetime Superalgebra in AdS_4 \times S^7 via Supermembrane Probe (1999)

Furuuchi, Kazuyuki, Ohta, Nobuyoshi, Zhou, Jian-Ge

The spacetime superalgebra via the supermembrane probe in the background of AdS_4 \times S^7 is discussed to the lowest order in the spinor coordinate $\t$. To obtain the correct spacetime...

Thermalization of Poincar\'{e} Vacuum State and Fermion Emission from AdS_3 Black Holes in Bulk-Boundary Correspondence (1998)

AdS$_3$/CFT Correspondence, Poincar\'{e} Vacuum State and Greybody Factors in BTZ Black Holes (1998)

The greybody factors for spin 1/2 particles in the BTZ black holes are discussed from 2D CFT in bulk-boundary correspondence. It is found that the initial state of spin 1/2 particle in the BTZ black...

Three-Dimensional Gauge Dynamics from Brane Configurations with (p,q)-Fivebrane (1998)

The greybody factors in BTZ black holes are evaluated from 2D CFT in the spirit of AdS$_3$/CFT correspondence. The initial state of black holes in the usual calculation of greybody factors by...

Kitao, Takuhiro, Ohta, Kazutoshi, Ohta, Nobuyoshi

We study three-dimensional gauge dynamics by using type IIB superstring brane configurations, which can be obtained from the M-theory configuration of M2-branes stretched between two M5-branes with...

Fermionic Zero Mode and String Creation between D4-Branes at Angles (1998)

Kitao, Takuhiro, Ohta, Nobuyoshi, Zhou, Jian-Ge

We study the creation of a fundamental string between D4-branes at angles in string theory. It is shown that $R(-1)^{F}$ part of the one-loop potential of open string changes its sign due to the...

Euclidean Path Integral, D0-Branes and Schwarzschild Black Holes in Matrix Theory (1998)

Creation of Fundamental String in M(atrix) Theory (1997)

The partition function in Matrix theory is constructed by Euclidean path integral method. The D0-branes, which move around in the finite region with a typical size of Schwarzschild radius, are chosen...

Ohta, Nobuyoshi, Shimizu, Takashi, Zhou, Jian-Ge

The potential between two D4-branes at angles with partially unbroken supersymmetry is computed, and is used to discuss the creation of a fundamental string when two such D4-branes cross each other...

Supersymmetry of M-Branes at Angles (1997)

Ohta, Nobuyoshi, Townsend, Paul K.

We determine the possible fractions of supersymmetry preserved by two intersecting M-5-branes. These include the fractions 3/32 and 5/32 which have not occurred previously in intersecting brane...

Realization of D4-Branes at Angles in Super Yang-Mills Theory (1997)

Low Energy Theorems in N=1 Supersymmetric Theory (1997)

An explicit solution in super Yang-Mills theory, which after T-duality describes two sets of D4-branes at angles, is constructed. The gauge configuration possesses 3/16 unbroken supersymmetry for the...

Higashijima, Kiyoshi, Nitta, Muneto, Ohta, Kazutoshi, Ohta, Nobuyoshi

In N=1 supersymmetric theories, quasi Nambu-Goldstone (QNG) bosons appear in addition to ordinary Nambu-Goldstone (NG) bosons when the global symmetry G breaks down spontaneously. We investigate...

Towards the Classification of Non-Marginal Bound States of M-branes and Their Construction Rules (1997)

Intersection Rules for Non-Extreme $p$-Branes (1997)

We present a systematic analysis of possible bound states of M-brane solutions (including waves and monopoles) by using the solution generating technique of reduction of M-brane to 10 dimensions, use...

Non-Extreme Black Holes from Intersecting M-Branes (1997)

We give a model-independent derivation of general intersecting rules for non-extreme $p$-branes in arbitrary dimensions $D$. This is achieved by directly solving bosonic field equations for...

Ohta, Nobuyoshi, Shimizu, Takashi

We investigate the possibility of extending non-extreme black hole solutions made of intersecting M-branes to those with two non-extreme deformation parameters, similar to Reissner-Nordstr{\o}m...

A Note on Consistent Anomalies (1997)

Baulieu, Laurent, Laroche, Celine, Ohta, Nobuyoshi, Picco, Marco

Within a BRST formulation, we determine the expressions of the consistent anomaly for superstrings with extended worldsheet supersymmetries of rank N. We consider the O(N) superconformal algebras up...

A Note on Consistent Anomalies (1997)

Baulieu, Laurent, Laroche, Celine, Ohta, Nobuyoshi, Picco, Marco

Within a BRST formulation, we determine the expressions of the consistent anomaly for superstrings with extended worldsheet supersymmetries of rank N. We consider the O(N) superconformal algebras up...

Worldsheets with Extended Supersymmetry (1996)

Baulieu, Laurent, Ohta, Nobuyoshi

We determine the equations which govern the gauge symmetries of worldsheets with local supersymmetry of arbitrary rank $(N,N')$, and their possible anomalies. Both classical and ghost conformally...

All the Exact Solutions of Generalized Calogero-Sutherland Models (1996)

Exact Solutions of Generalized Calogero-Sutherland Models -- BC_N and C_N cases (1996)

A collective field method is extended to obtain all the explicit solutions of the generalized Calogero-Sutherland models that are characterized by the roots of all the classical groups, including the...

Kojima, Masamichi, Ohta, Nobuyoshi

Using a collective field method, we obtain explicit solutions of the generalized Calogero-Sutherland models that are characterized by the roots of the classical groups $B_N$ and $C_N$. Starting from...

UNIVERSAL STRING AND SMALL $N=4$ SUPERSTRING (1995)

Ohta, Nobuyoshi, Shimizu, Takashi

It was previously shown that most of the superstrings can be obtained from those with higher world-sheet supersymmetry as spontaneously broken phases. In this paper, we show that the small $N=4$...

Note on W3 Realizations of the Bosonic String (1994)

Bastianelli, Fiorenzo, Ohta, Nobuyoshi

In order to investigate to what extent string theories are different vacua of a general string theory (the ``universal string"), we discuss realizations of the bosonic string as particular background...

Embeddings for Non-Critical Superstrings (1994)

Berkovits, Nathan, Ohta, Nobuyoshi

It was previously shown that at critical central charge, $N$-extended superstrings can be embedded in $(N+1)$-extended superstrings. In other words, $(N=0,c=26)\to (N=1,c=15)\to (N=2,c=6)\to...

A Hierarchy of Superstrings (1994)

Bastianelli, Fiorenzo, Ohta, Nobuyoshi, Petersen, Jens Lyng

We construct a hierarchy of supersymmetric string theories by showing that the general N-extended superstrings may be viewed as a special class of the (N+1)-extended superstrings. As a side result,...

The BRST Operator for the Large $N=4$ Superconformal Algebra (1994)

Bastianelli, Fiorenzo, Ohta, Nobuyoshi

We review the detailed structure of the large $N=4$ superconformal algebra, and construct its BRST operator which constitutes the main object for analyzing $N=4$ strings. We then derive the general...

Toward the Universal Theory of Strings (1994)

Bastianelli, Fiorenzo, Ohta, Nobuyoshi, Petersen, Jens Lyng

We show that the $N=2$ superstrings may be viewed as a special class of the $N=4$ superstrings and demonstrate their equivalence. This allows us to realize all known string theories based on linear...

$N=1$ from $N=2$ Superstrings (1993)

Ohta, Nobuyoshi, Petersen, Jens Lyng

We give a simple proof that a particular class of $N=2$ superstrings are equivalent to the $N=1$ superstrings. This is achieved by constructing a similarity transformation which transforms the $N=2$...

Bosonization of a Topological Coset Model and Non-Critical String Theory (1993)

Ohta, Nobuyoshi, Suzuki, Hisao

We analyze the relation between a topological coset model based on super $SL(2,R)/U(1)$ coset and non-critical string theory by using free field realization. We show that the twisted $N=2$ algebra of...

BRST Analysis of Physical States in Two-Dimensional Black Hole (1993)

Itoh, Katsumi, Kunitomo, Hiroshi, Ohta, Nobuyoshi, Sakaguchi, Makoto

We study the BRST cohomology for $SL(2,R)/U(1)$ coset model, which describes an exact string black hole solution. It is shown that the physical spectrum could contain not only the extra discrete...

Discrete States in Two-Dimensional Quantum Gravity (1992)