4,353 research outputs found
Topology and chiral symmetry in finite temperature QCD
We investigate the realization of chiral symmetry in the vicinity of the
deconfinement transition in quenched QCD using overlap fermions. Via the index
theorem obeyed by the overlap fermions, we gain insight into the behavior of
topology at finite temperature. We find small eigenvalues, clearly separated
from the bulk of the eigenvalues, and study the properties of their
distribution. We compare the distribution with a model of a dilute gas of
instantons and anti-instantons and find good agreement.Comment: 3 pages with 3 ps figures; to appear in the proceedings of Lattice
'99, Pisa, Italy, June 29 -- July 3, 1999. LATTICE99(topology
Thermodynamics with Dynamical Clover Fermions
We investigate the finite temperature behavior of nonperturbatively improved
clover fermions on lattices with temporal extent N_t=4 and 6. Unfortunately in
the gauge coupling range, where the clover coefficient has been determined
nonperturbatively, the finite temperature crossover/transition occurs at heavy
pseudoscalar masses and large pseudoscalar to vector meson mass ratios.
However, on an N_t=6 lattice the thermal crossover for the improved fermions is
much smoother than for unimproved Wilson fermions and no strange metastable
behavior is observed.Comment: 8 pages, LaTeX, 5 postscript figure
Probing the QCD vacuum with overlap fermions
We use low lying eigenvectors of the overlap-Dirac operator as a probe of the
QCD vacuum. If instantons play a significant role one would expect the low
lying eigenmodes of the overlap-Dirac operator to consist mainly of the mixed
``would be zero modes''. Then, the eigenmodes should exhibit local chirality.
Studying a recently introduced local chirality parameter, we find evidence
supporting this picture.Comment: LaTeX, 5 pages, 5 postscript figures. Talk given by U.M. Heller at
the Workshop on Lattice Hadron Physics ``LHP2001'', July 9 -- 18, 2001,
Cairns, Australi
Overlap Dirac Operator, Eigenvalues and Random Matrix Theory
The properties of the spectrum of the overlap Dirac operator and their
relation to random matrix theory are studied. In particular, the predictions
from chiral random matrix theory in topologically non-trivial gauge field
sectors are tested.Comment: 3 pages latex with 1 postscript figure. Talk presented at
LATTICE99(topology
Topology and Chiral Symmetry in QCD with Overlap Fermions
We briefly review the overlap formalism for chiral gauge theories, the
overlap Dirac operator for massless fermions and its connection to domain wall
fermions. We describe properties of the overlap Dirac operator, and methods to
implement it numerically. Finally, we give some examples of quenched
calculations of chiral symmetry breaking and topology with overlap fermions.Comment: 12 pages with 6 ps figures; crckapb.sty included; to appear in the
proceedings of the workshop "Lattice Fermions and Structure of the Vacuum",
Oct 5-9, Dubna, Russi
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