1,276 research outputs found
Relation between Confinement and Chiral Symmetry Breaking in Temporally Odd-number Lattice QCD
In the lattice QCD formalism, we investigate the relation between confinement
and chiral symmetry breaking. A gauge-invariant analytical relation connecting
the Polyakov loop and the Dirac modes is derived on a temporally odd-number
lattice, where the temporal lattice size is odd, with the normal (nontwisted)
periodic boundary condition for link-variables. This analytical relation
indicates that low-lying Dirac modes have little contribution to the Polyakov
loop, and it is numerically confirmed at the quenched level in both confinement
and deconfinement phases. This fact indicates no direct one-to-one
correspondence between confinement and chiral symmetry breaking in QCD. Using
the relation, we also investigate the contribution from each Dirac mode to the
Polyakov loop. In the confinement phase, we find a new "positive/negative
symmetry" of the Dirac-mode matrix element of the link-variable operator, and
this symmetry leads to the zero value of the Polyakov loop. In the
deconfinement phase, there is no such symmetry and the Polyakov loop is
nonzero. Also, we develop a new method for spin-diagonalizing the Dirac
operator on the temporally odd-number lattice modifying the Kogut-Susskind
formalism.Comment: 15pages, 9 figure
Off-diagonal Gluon Mass Generation and Infrared Abelian Dominance in Maximally Abelian Gauge in SU(3) Lattice QCD
In SU(3) lattice QCD formalism, we propose a method to extract gauge fields
from link-variables analytically. With this method, we perform the first study
on effective mass generation of off-diagonal gluons and infrared Abelian
dominance in the maximally Abelian (MA) gauge in the SU(3) case. Using SU(3)
lattice QCD, we investigate the propagator and the effective mass of the gluon
fields in the MA gauge with U(1)_3 \timesU(1)_8 Landau gauge fixing. The
Monte Carlo simulation is performed on at =5.7, 5.8 and 6.0 at
the quenched level. The off-diagonal gluons behave as massive vector bosons
with the approximate effective mass in the region of fm, and the propagation is
limited within a short range, while the propagation of diagonal gluons remains
even in a large range. In this way, infrared Abelian dominance is shown in
terms of short-range propagation of off-diagonal gluons. Furthermore, we
investigate the functional form of the off-diagonal gluon propagator. The
functional form is well described by the four-dimensional Euclidean Yukawa-type
function with
for fm. This also indicates that the spectral function of
off-diagonal gluons has the negative-value region
Magnetic-Field-Induced 4f-Octupole in CeB6 Probed by Resonant X-ray Diffraction
CeB6, a typical Gamma_8-quartet system, exhibits a mysterious
antiferroquadrupolar ordered phase in magnetic fields, which is considered as
originating from the T_{xyz}-type magnetic octupole moment induced by the
field. By resonant x-ray diffraction in magnetic fields, we have verified that
the T_{xyz}-type octupole is indeed induced in the 4f-orbital of Ce with a
propagation vector (1/2, 1/2, 1/2), thereby supporting the theory. We observed
an asymmetric field dependence of the intensity for an electric quadrupole (E2)
resonance when the field was reversed, and extracted a field dependence of the
octupole by utilizing the interference with an electric dipole (E1) resonance.
The result is in good agreement with that of the NMR-line splitting, which
reflects the transferred hyperfine field at the Boron nucleus from the
anisotropic spin distribution of Ce with an O_{xy}-type quadrupole. The
field-reversal method used in the present study opens up the possibility of
being widely applied to other multipole ordering systems such as NpO2,
Ce_{x}La_{1-x}B_{6}, SmRu_{4}P_{12}, and so on.Comment: 5 pages, 4 figures, submitte
A unified origin for the 3D magnetism and superconductivity in NaCoO
We analyze the origin of the three dimensional (3D) magnetism observed in
nonhydrated Na-rich NaCoO within an itinerant spin picture using a 3D
Hubbard model. The origin is identified as the 3D nesting between the inner and
outer portions of the Fermi surface, which arise due to the local minimum
structure of the band at the -A line. The calculated spin wave
dispersion strikingly resembles the neutron scattering result. We argue that
this 3D magnetism and the spin fluctuations responsible for superconductivity
in the hydrated systems share essentially the same origin.Comment: 5pages, 6figure
- …