214 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
Meson-Meson and Meson-Baryon Interactions in Lattice QCD
We study the meson-meson and meson-baryon interactions in lattice QCD. The
simulation is performed on 20^3 * 24 lattice at \beta=5.7 using Wilson gauge
action and Wilson fermion at the quenched level. By adopting one static quark
for each hadron as "heavy-light meson" and "heavy-light-light baryon", we
define the distance of two hadrons and extract the inter-hadron potential
from the energy difference of the two-particle state and its asymptotic state.
We find that both of the meson-meson and meson-baryon potentials are
nontrivially weak for the whole range of 0.2 fm <= r <= 0.8 fm. The effect of
including/excluding the quark-exchange diagrams is found to be marginal.Comment: Talk given at Particles and Nuclei International Conference
(PANIC05), Santa Fe, NM, USA, 24-28 Oct. 2005. 3 pages, 2 figure
The Determination of the Quark-Gluon Mixed Condensate (anti-Q sigma G Q) from Lattice QCD
We study the quark-gluon mixed condensate g, using the
SU(3)c lattice QCD with the Kogut-Susskind fermion at the quenched level. We
generate 100 gauge configurations on the 16^4 lattice with \beta = 6.0, and
perform the measurement of the mixed condensate at 16 points in each gauge
configuration for each current quark mass of m_q=21, 36, 52 MeV. Using the 1600
data for each m_q, we find the ratio between the mixed condensate and the quark
condensate, m_0^2 = g / \simeq 2.5 GeV^2 at the
lattice scale of 1/a \simeq 2 GeV in the chiral limit. The large value of the
mixed condensate suggests its importance in the operator product expansions in
QCD. We study also chiral restoration at finite temperature in terms of the
mixed condensate, which is another chiral order parameter. We present the
lattice QCD results of the mixed condensate at finite temperature.Comment: 5 pages, Talk given at Tokyo-Adelaide Joint Workshop on Quarks,
Astrophysics and Space physics, Tokyo, Japan, Jan.6 - Jan.10, 200
Multi-Quarks and Two-Baryon Interaction in Lattice QCD
We study multi-quark (3Q,4Q,5Q) systems in lattice QCD. We perform the
detailed studies of multi-quark potentials in lattice QCD to clarify the
inter-quark interaction in multi-quark systems. We find that all the
multi-quark potentials are well described by the OGE Coulomb plus multi-Y-type
linear potential, i.e., the multi-Y Ansatz. For multi-quark systems, we observe
lattice QCD evidences of ``flip-flop'', i.e., flux-tube recombination. These
lattice QCD studies give an important bridge between elementary particle
physics and nuclear physics.Comment: A talk given at Particles and Nuclei International
Conference(PANIC05), Santa Fe, NM, Oct. 24-28, 2005. 3 pages, 6 figure
Quark tensor charge and electric dipole moment within the Schwinger-Dyson formalism
We calculate the tensor charge of the quark in the QCD-like theory in the
Landau gauge using the Schwinger-Dyson formalism. It is found that the dressed
tensor charge of the quark is significantly suppressed against the bare quark
contribution, and the result agrees qualitatively with the analyses in the
collinear factorization approach and lattice QCD. We also analyze the quark
confinement effect with the phenomenological strong coupling given by
Richardson, and find that this contribution is small. We show that the
suppression of the quark tensor charge is due to the superposition of the spin
flip of the quark arising from the successive emission of gluons which dress
the tensor vertex. We also consider the relation between the quark and the
nucleon electric dipole moments by combining with the simple constituent quark
model.Comment: 16 pages, 11 figures. arXiv admin note: text overlap with
arXiv:1401.285
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