3,000 research outputs found
Baryon Spectroscopy on the Lattice
Recent lattice QCD calculations of the baryon spectrum are outlined.Comment: Plenary contribution to Baryons 2002, Jefferson Lab, March 2002, 9
pages, 7 figure
Two Photon Decays of Charmonia from Lattice QCD
We make the first calculation in lattice QCD of two-photon decays of mesons.
Working in the charmonium sector, using the LSZ reduction to relate a photon to
a sum of hadronic vector eigenstates, we compute form-factors in both the
space-like and time-like domains for the transitions and . At the on-shell point we find
approximate agreement with experimental world-average values.Comment: Replaced with version to be published in PRL. Expanded discussion of
possible systematic error
The Chroma Software System for Lattice QCD
We describe aspects of the Chroma software system for lattice QCD
calculations. Chroma is an open source C++ based software system developed
using the software infrastructure of the US SciDAC initiative. Chroma
interfaces with output from the BAGEL assembly generator for optimised lattice
fermion kernels on some architectures. It can be run on workstations, clusters
and the QCDOC supercomputer.Comment: poster presented at Lattice2004(machines
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
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