A conjecture on the relation between the cubic Hodge integrals and the
topological vertex in topological string theory is resolved. A central role is
played by the notion of generalized shift symmetries in a fermionic realization
of the two-dimens...

The perspective of Kac-Schwarz operators is introduced to the authors'
previous work on the quantum mirror curves of topological string theory in
strip geometry and closed topological vertex. Open string amplitudes on each
leg of the web diagram o...

The closed topological vertex is the simplest ``off-strip'' case of
non-compact toric Calabi-Yau threefolds with acyclic web diagrams. By the
diagrammatic method of topological vertex, open string amplitudes of
topological string theory therein ca...

J. Phys. A: Math. Theor. 45 025403 (38pp) Jan 2012 [Refereed]

We study the thermodynamic limit of random partition models for the instanton
sum of 4D and 5D supersymmetric U(1) gauge theories deformed by some physical
observables. The physical observables correspond to external potentials in the
statistical ...

We study an extension of the Seiberg-Witten theory of
supersymmetric Yang-Mills on . We investigate
correlation functions among loop operators. These are the operators analogous
to the Wilson loops enc...

Commun. Math. Phys. 285(2) 445-468 Jan 2009 [Refereed]

Searching for the integrable structures of supersymmetric gauge theories and
topological strings, we study melting crystal, which is known as random plane
partition, from the viewpoint of integrable systems. We show that a series of
partition func...

Int. J. Mod. Phys. A 22(05) 937-984 Feb 2007 [Refereed]

We study a statistical model of random plane partitions. The statistical
model has interpretations as five-dimensional supersymmetric
SU(N) Yang-Mills on and as Kähler gravity on local
SU(N) geometry. At ...

We study Kähler gravity on local SU(N) geometry and describe precise
correspondence with certain supersymmetric gauge theories and random plane
partitions. The local geometry is discretized, via the geometric quantization,
to a foam of an infi...

Nucl. Phys. B 715(1-2) 275-303 May 2005 [Refereed]

A model of random plane partitions which describes five-dimensional
supersymmetric SU(N) Yang-Mills is studied. We compute the wave
functions of fermions in this statistical model and investigate their
thermodynamic limits or the s...

Five-dimensional supersymmetric Yang-Mills theories are
investigated from the viewpoint of random plane partitions. It is shown that
random plane partitions are factorizable as q-deformed random partitions so
that they admit the in...

Prog. Theor. Phys. 110(2) 285-384 Mar 2003 [Refereed]

System of a D-brane in bosonic string theory on a constant field
background is studied in order to obtain further insight into the bulk-boundary
duality. Boundary states which describe arbitrary numbers of open-string
tachyons and gluons are g...

We investigate classical bosonic open-string field theory from the
perspective of the Wilson renormalization group of world-sheet theory. The
microscopic action is identified with Witten's covariant cubic action and the
short-distance cut-off scal...

Prog. Theor. Phys. 104(2) 439-458 Dec 2000 [Refereed]

We discuss the microscopic states of the extremal BTZ black holes. Degeneracy
of the primary states corresponding to the extremal BTZ black holes in the
boundary N=(4,4) SCFT is obtained by utilizing the elliptic genus and the
unitary representati...

Prog. Theor. Phys. 102(4) 867-896 May 1999 [Refereed]

A quantization of (2+1)-dimensional gravity with negative cosmological
constant is presented and quantum aspects of the (2+1)-dimensional black holes
are studied thereby. The quantization consists of two procedures. One is
related with quantizatio...

Mod. Phys. Lett. A 14(02) 147-160 Jan 1999 [Refereed]

As a toy model to search for Hamiltonian formalism of the
correspondence, we examine a Hamiltonian formulation of the
correspondence emphasizing unitary representation theory of the symmetry. In
the course of a canonical qu...

We investigate the brane exchange in the framework of N=2 MQCD by using a
specific family of M fivebrane configurations relevant to describe the baryonic
branch root. An exchange of M fivebranes is realized in the Taub-NUT geometry
and controlled ...

Toshio Nakatsu, Kazutoshi Ohta, Takashi Yokono, Yuhsuke Yoshida

Nucl. Phys. B 519(1-2) 159-179 May 1998 [Refereed]

Higgs branch of N=2 SQCD is studied from the M theory viewpoint. With a
differential geometrical proof of the s-rule besides an investigation on the
global symmetry of M theory brane configurations, an exact description of the
baryonic and non-bar...

Int. J. Mod. Phys. A 13(6) 923-963 Mar 1998 [Refereed]

A framework of second-quantization of D5-branes is proposed. It is based on
the study of topology of the moduli space of their low energy effective
worldvolume theory. Among the topological cycles which resolve singularities
caused by overlapping ...

Toshio Nakatsu, Kazutoshi Ohta, Takashi Yokono, Yuhsuke Yoshida

Mod. Phys. Lett. A 13(4) 293-301 Feb 1998 [Refereed]

We study configurations of a single fivebrane in the geometry where is the Taub-NUT space. Taking the IIA limit at each value
of their modulus, two possibilities of the IIA configuration are revealed. One
consists of a...

Toshio Nakatsu, Kazutoshi Ohta, Takashi Yokono, Yuhsuke Yoshida

Nucl. Phys. B 519 159-179 Jul 1997 [Refereed]

Higgs branch of N=2 SQCD is studied from the M theory viewpoint. With a
differential geometrical proof of the s-rule besides an investigation on the
global symmetry of M theory brane configurations, an exact description of the
baryonic and non-bar...

We construct the six-dimensional topological field theory appropriate to
describe the ground-state configurations of D5-branes. A close examination on
the degenerations of D5-branes gives us the physical observables which can be
regarded as the Po...

Int.J.Mod.Phys. A 11(31) 5505-5518 Dec 1996 [Refereed]

Seiberg-Witten solutions of four-dimensional supersymmetric gauge theories
possess rich but involved integrable structures. The goal of this paper is to
show that an isomonodromy problem provides a unified framework for
understanding those various...

Mod.Phys.Lett. A 11(2) 157-168 Jan 1996 [Refereed]

The exact solution of supersymmetric Yang-Mills theory is
studied in the framework of the Whitham hierarchies. The solution is identified
with a homogeneous solution of a Whitham hierarchy. This integrable hierarchy
(Whitham-Toda hie...

The quantum and classical aspects of a deformed matrix model proposed by
Jevicki and Yoneya are studied. String equations are formulated in the
framework of Toda lattice hierarchy. The Whittaker functions now play the role
of generalized Air...

The partition function of topological string, the coupled system of
topological gravity and topological minimal matter , is proposed in
the framework of KP hierarchy. It is specified by the elements of
which consti...

Mod.Phys.Lett.A 9(35) 3313-3324 Nov 1994 [Refereed]

The analogue of the string equation which specifies the partition function of
string with a compactification radius \bf{Z} is described in the framework of the Toda lattice hierarchy.

We study the relation between topological string theory and singularity
theory using the partition function of topological string defined by
matrix integral of Kontsevich type. Genus expansion of the free energy is
considered, and the ge...

A class of two-dimensional topological conformal field theories (TCFTs) is
studied within the framework of gauged WZW models in order to gain some
insights on the global geometrical nature of TCFTs. The BRST quantizations of
topological G/H gauged...

We study the "topological gauged WZW model associated with
",which is defined as the twisted version of the corresponding
supersymmetric gauged WZW model. It is shown that this model is equivalent to a
topological conformal field theor...

Mod. Phys. Lett. A 7(24) 2215-2222 Aug 1992 [Refereed]

We study the twisted version of the supersymmetric
$G/T=SU(n)/U(1)^{\otimes(n-1)} gauged Wess-Zumino-Witten model. By studying its
fixed points under BRST transformation this model is shown to be reduced to a
simple topological field theory, that ...

We discuss the Atiyah-Drinfeld-Hitchin-Manin (ADHM) construction of U(N)
instantons in noncommutative (NC) space and prove the one-to-one correspondence
between moduli spaces of the noncommutative instantons and the ADHM data,
together with an ori...

This is a review of the authors' recent results on an integrable structure of
the melting crystal model with external potentials. The partition function of
this model is a sum over all plane partitions (3D Young diagrams). By the
method of transfe...

Int. J. Mod. Phys. A 23 2332-2342 Jun 2008 [Refereed][Invited]

We study loop operators of SYM in background.
For the case of U(1) theory, the generating function of correlation functions
of the loop operators reproduces the partition function of melting crystal
model with externa...

Boundary interactions of closed-string with open-strings are examined
intended to provide a constructive formulation of boundary string field theory.
As an illustration, we consider the BPS -brane of the type II superstring in
a constant NS-NS ...

arxiv.org/abs/hep-th/9805107v1 Lecture in the Second Winter School on ``Branes, Fields And Mathematical Physics" at the APCTP (Feb.9-20, 1998) 1998 [Invited]

We review M-theory description of 4d N=2 SQCD. Configurations of M-theory
fivebranes relevant to describe the moduli spaces of the Coulomb and Higgs
branches are studied using the Taub-NUT geometry. Minimal area membranes
related with the BPS stat...

Ministry of Education, Culture, Sports, Science and Technology: Grants-in-Aid for Scientific Research(基盤研究(C))

Project Year: Apr 2003 - Mar 2007 Investigator(s): Toshio NAKATSU

(i)We exploit the boundary state formalism to investigate duality between open-and closed-strings in superstring theory. By using the off-shell interactions of open-and closed-strings developed in our for- malism, we show that in the background of...

The purpose of this research was to study superstring theory and moduli spaces of supersymmetric gauge theories ('superstring geometry') by various mathematical and physical considerations. and verify the superstring duality in quantitative and ri...

Ministry of Education, Culture, Sports, Science and Technology: Grants-in-Aid for Scientific Research(基盤研究(C))

Project Year: Apr 1997 - Mar 2000 Investigator(s): Takahiro KUBOTA

The decay rates of Higgs boson into gauge boson pairs were evaluated in the two-Higgs doublet model including radiative corrections. We have found that the effects of heavy unknown particles through radiative corrections are always subleading. Thi...

Symmetry breaking in field theory is caused by some instability. Instability in one-particle problem triggers classical instability. In classically stable systems, symmetry sometimes breaks down by quantum instability. In these cases, instability ...