14,628 research outputs found
Perturbative Improvement for Lattice QCD: An Update
Recent developments in the Symanzik improvement program for lattice QCD are
reviewed.Comment: Invited talk at the workshop on "Lattice QCD on Parallel Computers"
(Tsukuba, March 1997). One file producing 12 pages; LaTe
Mass renormalisation for improved staggered quarks
Improved staggered quark actions are designed to suppress flavour changing
strong interactions. We discuss the perturbation theory for this type of
actions and show the improvements to reduce the quark mass renormalisation
compared to naive staggered quarks. The renormalisations are of similar size as
for Wilson quarks.Comment: LaTeX, 3 pages, Lattice2001(spectrum
Mean link versus average plaquette tadpoles in lattice NRQCD
We compare mean-link and average plaquette tadpole renormalization schemes in
the context of the quarkonium hyperfine splittings in lattice NRQCD.
Simulations are done for the three quarkonium systems , , and
. The hyperfine splittings are computed both at leading and at
next-to-leading order in the relativistic expansion. Results are obtained at a
large number of lattice spacings. A number of features emerge, all of which
favor tadpole renormalization using mean links. This includes much better
scaling of the hyperfine splittings in the three quarkonium systems. We also
find that relativistic corrections to the spin splittings are smaller with
mean-link tadpoles, particularly for the and systems. We
also see signs of a breakdown in the NRQCD expansion when the bare quark mass
falls below about one in lattice units (with the bare quark masses turning out
to be much larger with mean-link tadpoles).Comment: LATTICE(heavyqk) 3 pages, 2 figure
Highly Improved Naive and Staggered Fermions
We present a new action for highly improved staggered fermions. We show that
perturbative calculations for the new action are well-behaved where those of
the conventional staggered action are badly behaved. We discuss the effects of
the new terms in controlling flavor mixing, and discuss the design of operators
for the action.Comment: Contribution to Lattice2001(improvement); 3 page
A review of heavy-heavy spectroscopy
Calculations of the heavy-heavy spectrum present a good opportunity for
precision tests of QCD using lattice techniques. All methods make use of a
non-relativistic expansion of the action and its systematic improvement to
remove lattice artefacts. There was convincing demonstration this year that
these methods work and that the associated perturbation theory is well-behaved.
Comparison to experimental results yields an accurate value for the lattice
spacing, a, a key result in the determination of \alpha_{s}, and (for the first
time this year) the mass of the b quark (4.7(1) GeV).Comment: talk at Lattice'93, Dallas. 6 pages of latex espcrc2.sty needed and
figures on reques
Nonperturbative ``Lattice Perturbation Theory''
We discuss a program for replacing standard perturbative methods with Monte
Carlo simulations in short distance lattice gauge theory calculations.Comment: 3 pages, uuencoded Latex file, two embedded figures and .sty file
include
Second Order Perturbation Theory for Improved Gluon and Staggered Quark Actions
We present the results of our perturbative calculations of the static quark
potential, small Wilson loops, the static quark self energy, and the mean link
in Landau gauge. These calculations are done for the one loop Symanzik improved
gluon action, and the improved staggered quark action.Comment: 3 pages, LaTeX, Lattice2001(improvement
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