Kazunori Itakura

J-GLOBAL         Last updated: Oct 17, 2018 at 18:11
Kazunori Itakura

Research Areas


Published Papers

Kei Suzuki, Shigehiro Yasui, Kazunori Itakura
Phys. Rev. D 96, 114007 (2017)      Aug 2017   [Refereed]
Koichi Hattori, Kazunori Itakura, Sho Ozaki
   Jun 2017   [Refereed]
Shigehiro Yasui, Kei Suzuki, Kazunori Itakura
Phys. Rev. D 96, 014016 (2017)      Mar 2017   [Refereed]
We investigate properties of the ground state of a light quark matter with
heavy quark impurities. This system exhibits the "QCD Kondo effect" where the
interaction strength between a light quark near the Fermi surface and a heavy
quark increases ...
H.Fujii, K.Itakura and C.Nonaka,
Nucl.Phys. A967 (2017) 704-707      2017   [Refereed]
Shigehiro Yasui, Kei Suzuki, Kazunori Itakura
   Apr 2016
We discuss the ground state of a quark matter containing heavy quarks as
impurities in a simple model which exhibits the QCD Kondo effect. The model
includes a current-current interaction with the color exchange between a light
quark (Tex) and ...
Sho Ozaki, Kazunori Itakura, Yoshio Kuramoto
Phys. Rev. D 94, 074013 (2016)      Sep 2015
The "QCD Kondo effect" stems from the color exchange interaction in QCD with
non-Abelian property, and can be realized in a high-density quark matter
containing heavy-quark impurities. We propose a novel type of the QCD Kondo
effect induced by a s...
Koichi Hattori, Kazunori Itakura
   Sep 2015
We discuss properties of photons in extremely strong magnetic fields induced
by the relativistic heavy-ion collisions. We investigate the vacuum
birefringence, the real-photon decay, and the photon splitting which are all
forbidden in the ordinary...
Sho Ozaki, Takashi Arai, Koichi Hattori, Kazunori Itakura
Phys. Rev. D 92, 016002 (2015)      Apr 2015
We derive an analytic expression for one-loop effective action of QCD+QED at
zero and finite temperatures by using the Schwinger's proper time method. The
result is a nonlinear effective action not only for electromagnetic and
Koichi Hattori, Kazunori Itakura, Sho Ozaki, Shigehiro Yasui
Phys. Rev. D 92, 065003 (2015)      Apr 2015
We show that the Kondo effect occurs in light quark matter which contains
heavy quarks as impurities. We consider a scattering between a heavy-flavor
impurity and a light quark near a Fermi surface which is mediated by
gluon-exchange interactions....
Wei-Tian Deng, Hirotsugu Fujii, Kazunori Itakura, Yasushi Nara
   Oct 2014
We develop a Monte-Carlo event generator based on combination of a parton
production formula including the effects of parton saturation (called the DHJ
formula) and hadronization process due to the Lund string fragmentation model.
This event gener...
Hidetoshi Taya, Hirotsugu Fujii, Kazunori Itakura
Phys. Rev. D 90, 014039 (2014)      May 2014
We investigate electron-positron pair creation from the vacuum in a pulsed
electric background field. Employing the Sauter-type pulsed field Tex with height Tex and width Tex, we demonstrate
explicitly the interpl...
Yohei Saito, Hirotsugu Fujii, Kazunori Itakura, Osamu Morimatsu
   Sep 2013
We present an argument to support the existence of dissipative modes in
relativistic field theories. In an O(N) Tex theory in spatial dimension
Tex, a relaxation constant Tex of a two-point function in an infrared
region is shown...
Koichi Hattori, Kazunori Itakura
Ann. Phys. 334 (2013) 58-82      Dec 2012
We compute the refractive indices of a photon propagating in strong magnetic
fields on the basis of the analytic representation of the vacuum polarization
tensor obtained in our previous paper. When the external magnetic field is
strong enough for...
Koichi Hattori, Kazunori Itakura
Ann. Phys. 330 (2013) 23-54      Sep 2012
Photons propagating in strong magnetic fields are subject to a phenomenon
called the "vacuum birefringence" where refractive indices of two physical
modes both deviate from unity and are different from each other. We compute the
vacuum polarizatio...
Kazunori Itakura, Koichi Hattori
   Jun 2012
We discuss potential attainability by the Hanbury Brown and Twiss (HBT)
interferometry of photons to probe the spacetime geometry of the primordial
plasma created by ultrarelativistic heavy-ion collisions. A possible effect to
distort the HBT imag...
Shigehiro Yasui, Yuji Hirono, Kazunori Itakura, Muneto Nitta
Phys.Rev.E87:052142,2013      Apr 2012
We extend our previous analysis on the exchange statistics of vortices having
a single Dirac fermion trapped in each core, to the case where vortices trap
two Dirac fermions with U(2) symmetry. Such a system of vortices with
non-Abelian Dirac ferm...
Yuji Hirono, Shigehiro Yasui, Kazunori Itakura, Muneto Nitta
Phys.Rev.B86:014508,2012      Mar 2012
We consider the exchange statistics of vortices, each of which traps an odd
number (Tex) of Majorana fermions. We assume that the fermions in a vortex
transform in the vector representation of the SO(N) group. Exchange of two
vortices turns out to...
Naoto Tanji, Kazunori Itakura
   Nov 2011
We discuss gluon production by the Schwinger mechanism in collinear
color-electric and magnetic fields which may be realized in pre-equilibrium
stages of ultra-relativistic heavy-ion collisions. Fluctuations of non-Abelian
gauge fields around a pu...
Shigehiro Yasui, Kazunori Itakura, Muneto Nitta
Nucl.Phys.B859:261-268,2012      Sep 2011
Topological superconductors classified as type D admit zero-energy Majorana
fermions inside vortex cores, and consequently the exchange statistics of
vortices becomes non-Abelian, giving a promising example of non-Abelian anyons.
On the other hand...
Yohei Saito, Hirotsugu Fujii, Kazunori Itakura, Osamu Morimatsu
   Aug 2011
We calculate the critical exponent Tex in the 1/N expansion of the
two-particle-irreducible (2PI) effective action for the O(N) symmetric Tex model in three spatial dimensions. The exponent Tex controls the behavior
of a two-point functi...
Shigehiro Yasui, Kazunori Itakura, Muneto Nitta
Phys.Rev.B83:134518,2011      Oct 2010
We discuss statistics of vortices having zero-energy non-Abelian Majorana
fermions inside them. Considering the system of multiple non-Abelian vortices,
we derive a non-Abelian statistics that differs from the previously derived
non-Abelian statis...
Shigehiro Yasui, Kazunori Itakura, Muneto Nitta
Phys.Rev.D81:105003,2010      Jan 2010
We study the internal structure of a non-Abelian vortex in color
superconductivity with respect to quark degrees of freedom. Stable non-Abelian
vortices appear in the Color-Flavor-Locked phase whose symmetry SU(3)_{c+L+R}
is further broken to SU(2...
Kazunori Itakura, Jun Ohkubo, Shin-ichi Sasa
J.Phys.A43:125001,2010      Dec 2009
A system-size expansion method is incorporated into the Doi-Peliti formalism
for stochastic chemical kinetics. The basic idea of the incorporation is to
introduce a new decomposition of unity associated with a so-called Cole-Hopf
transformation. T...
Kazunori Itakura, Osamu Morimatsu, Hiroshi Otomo
Phys.Rev.D77:014014,2008      Nov 2007
We discuss in detail the shear viscosity coefficient eta and the viscosity to
entropy density ratio eta/s of a hadronic gas comprised of pions and nucleons.
In particular, we study the effects of baryon chemical potential on eta and
eta/s. We solv...
K. Itakura
Nucl.Phys. A774 (2006) 277-286      Nov 2005
I discuss recent results on the Color Glass Condensate which is a dense
saturated gluonic state and appears as the universal picture of hadrons or
nuclei at very high energies.
K. Naito, S. Maedan, K. Itakura
Phys.Rev. D70 (2004) 096008      Jul 2004
We study the properties of light mesons in the scalar, pseudo-scalar, and
vector channels within the light-front quantization, by using the (one flavor)
Nambu--Jona-Lasinio model with vector interaction. After taking into account
the effects of ch...
Kazunori Itakura
J.Phys.G30:S989-S994,2004      Mar 2004
The proton structure function F_2(x,Q^2) for x < 0.01 and 0.045< Q^2 < 45
GeV^2, measured in the deep inelastic scattering at HERA, can be well described
within the framework of the Color Glass Condensate.
E. Iancu, K. Itakura, S. Munier
Phys.Lett.B590:199-208,2004      Oct 2003
We show that the HERA data for the inclusive structure function F_2(x,Q^2)
for x < 0.01 and 0.045 < Q^2 < 45 GeV^2 can be well described within the color
dipole picture, with a simple analytic expression for the dipole-proton
scattering amplitude,...
K. Naito, S. Maedan, K. Itakura
Phys.Lett. B583 (2004) 87-95      Aug 2003
We apply the light-front quantization to the Nambu--Jona-Lasinio model with
the vector interaction, and compute vector meson's mass and light-cone
wavefunction in the large N limit. Following the same procedure as in the
previous analyses for scal...
Kazunori Itakura, Yuri V. Kovchegov, Larry McLerran, Derek Teaney
Nucl.Phys.A730:160-190,2004      May 2003
We argue that the amount of baryon stopping observed in the central rapidity
region of heavy ion collisions at RHIC is proportional to the nuclear valence
quark distributions at small x. By generalizing Mueller's dipole model to
describe Reggeons ...
Edmond Iancu, Kazunori Itakura, Larry McLerran
Nucl.Phys.A724:181-222,2003      Dec 2002
We construct a Gaussian approximation to the effective theory for the Colour
Glass Condensate which describes correctly the gluon distribution both in the
low density regime at high transverse momenta (above the saturation scale
Tex), and in the...
Kazunori Itakura
Nucl.Phys. A715 (2003) 859-862      Sep 2002
We discuss a possibility of transition from color superconductivity of the
standard BCS type at high density, to Bose-Einstein Condensation (BEC) of
Cooper pairs at lower density. Examining two-flavor QCD over a wide range of
baryon density, we fo...
H. Abuki, T. Hatsuda, K. Itakura
   Jun 2002
The two-flavor color superconductivity is examined over a wide range of
baryon density with a single model. To study the structural change of Cooper
pairs, quark correlation in the color superconductor is calculated both in the
momentum space and ...
E. Iancu, K. Itakura, L. McLerran
Nucl.Phys.A708:327-352,2002      Mar 2002
We show that the evolution equations in QCD predict geometric scaling for
quark and gluon distribution functions in a large kinematical window, which
extends above the saturation scale up to momenta Tex of order Tex. For $Q^2 < Q^2...
Hiroaki Abuki, Tetsuo Hatsuda, Kazunori Itakura
Phys.Rev. D65 (2002) 074014      Sep 2001
The two-flavor color superconductivity is studied over a wide range of baryon
density with a single model. We pay a special attention to the spatial-momentum
dependence of the gap and to the spatial-structure of Cooper pairs. At
extremely high bar...
Katsuhiko Suzuki, Kazunori Itakura
Nucl.Phys.Proc.Suppl. 99A (2001) 230-233      Nov 2000
We study the hard color dipole-nucleon cross section within perturbative QCD
and discuss its relation to observables in diffractive leptoproduction of heavy
quarkonium. The dipole cross section calculated with the unintegrated gluon
density of the...
K. Itakura, S. Maedan
Phys.Rev. D62 (2000) 105016      Apr 2000
An investigation of dynamical chiral symmetry breaking on the light front is
made in the Nambu--Jona-Lasinio model with one flavor and N colors. Analysis of
the model suffers from extraordinary complexity due to the existence of a
"fermionic const...
K. Itakura, S. Maedan
Phys.Rev. D61 (2000) 045009      Jul 1999
Dynamical chiral symmetry breaking in the DLCQ method is investigated in
detail using a chiral Yukawa model closely related to the Nambu-Jona-Lasinio
model. By classically solving three constraints characteristic of the
light-front formalism, we s...
Kazunori Itakura
Prog.Theor.Phys. 98 (1997) 527-532      Jun 1997
We investigate how the gap equations are obtained in the light-front
formalism within the four-Fermi theories. Instead of the zero-mode constraint,
we find that the "fermionic constraints" on nondynamical spinor components are
responsible for symm...
K. Itakura, S. Maedan
Prog.Theor.Phys. 97 (1997) 635-652      Mar 1997
Spontaneous symmetry breaking of the light-front Gross-Neveu model is studied
in the framework of the discretized light-cone quantization. Introducing a
scalar auxiliary field and adding its kinetic term, we obtain a constraint on
the longitudinal...
Kazunori Itakura
Phys.Rev. D54 (1996) 2853-2862      Apr 1996
We derive a bosonic Hamiltonian from two dimensional QCD on the light-front.
To obtain the bosonic theory we find that it is useful to apply the boson
expansion method which is the standard technique in quantum many-body physics.
We introduce bilo...
Kazunori Itakura, Koichi Ohta
Phys.Rev. D50 (1994) 4145-4156      Jun 1994
We reexamine a unitary-transformation method of extracting a physical
Hamiltonian from a gauge field theory after quantizing all degrees of freedom
including redundant variables. We show that this {\it quantum Hamiltonian
reduction} method suffers...


Osamu Morimatsu, Hirotsugu Fujii, Kazunori Itakura, Yohei Saito
   Nov 2014
We study the dynamic critical exponent from effective and microscopic
theories. We employ a simple TDGL model, or model A in the classification of
Hohenberg and Halperin, as an effective theory and the imaginary time formalism
of the finite-temper...
Koichi Hattori, Kazunori Itakura, Sho Ozaki
   May 2013
We investigate decay and production of neutral pions in strong magnetic
fields. In the presence of strong magnetic fields, transition between a neutral
pion and a virtual photon becomes possible through the triangle diagram
relevant for the chiral...
Kazunori Itakura
   Oct 2005
We discuss the "odderon" exchange at high energy within the framework of the
Color Glass Condensate.
Kazunori Itakura
   Oct 2004
I give a brief review about the color glass condensate, which is the
universal form of hadrons and nuclei at high energies.
Kazunori Itakura
   Sep 2003
I discuss dome phenomenological consequences of the Color Glass formalism for
deep inelastic scattering.
E. Iancu, K. Itakura, L. McLerran
   May 2002
Geometric scaling is a novel scaling phenomenon observed in deep inelastic
scattering at small x: the total virtual photon-proton cross section depends
upon the two kinematical variables Q^2 and x only via their combination Q^2
R_0^2(x), with R_0^...
Soryushiron Kenkyu   94(6) F37-F40   Mar 1997
Kazunori Itakura
   Aug 1996
We investigate dynamical symmetry breaking of the Gross-Neveu model in the
light-front formalism without introducing auxiliary fields. While this system
cannot have zero-mode constraints, we find that a nontrivial solution to the
constraint on non...

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