728 research outputs found
Accumulating evidence for nonstandard leptonic decays of D_s mesons
The measured rate for D_s -> l nu decays, where l is a muon or tau, is larger
than the standard model prediction, which relies on lattice QCD, at the 3.8
sigma level. We discuss how robust the theoretical prediction is, and we show
that the discrepancy with experiment may be explained by a charged Higgs boson
or a leptoquark.Comment: 4 pages; v2 conforms with PRL versio
Continuing Progress on a Lattice QCD Software Infrastructure
We report on the progress of the software effort in the QCD Application Area
of SciDAC. In particular, we discuss how the software developed under SciDAC
enabled the aggressive exploitation of leadership computers, and we report on
progress in the area of QCD software for multi-core architectures.Comment: 5 Pages, to appear in the Proceedings of SciDAC 2008 conference,
(Seattle, July 13-17, 2008), Conference Poster Presentation Proceeding
Application of heavy-quark effective theory to lattice QCD: III. Radiative corrections to heavy-heavy currents
We apply heavy-quark effective theory (HQET) to separate long- and
short-distance effects of heavy quarks in lattice gauge theory. In this paper
we focus on flavor-changing currents that mediate transitions from one heavy
flavor to another. We stress differences in the formalism for heavy-light
currents, which are discussed in a companion paper, showing how HQET provides a
systematic matching procedure. We obtain one-loop results for the matching
factors of lattice currents, needed for heavy-quark phenomenology, such as the
calculation of zero-recoil form factors for the semileptonic decays . Results for the Brodsky-Lepage-Mackenzie scale are also
given.Comment: 35 pages, 17 figures. Program LatHQ2QCD to compute matching one-loop
coefficients available at http://theory.fnal.gov/people/kronfeld/LatHQ2QCD
Confining Configurations in QCD and Relation to Rigid Strings
The gauge field configurations of QCD gauge fields in the infrared regime are
obtained by magnetic symmetry condition. The effective dual action exhibits
dual Meissner effect with quarks included. A string representation of this
action corresponds to rigid string.Comment: 3 pages, Latex file, usepackage fleqn, espcrc2. Talk given in the
parallel session of the XVIII International Sympposium on Lattice Field
Theory, August 2000, held at Bangalore, Indi
Unquenching effects on the coefficients of the L\"uscher-Weisz action
The effects of unquenching on the perturbative improvement coefficients in
the Symanzik action are computed within the framework of L\"uscher-Weisz
on-shell improvement. We find that the effects of quark loops are surprisingly
large, and their omission may well explain the scaling violations observed in
some unquenched studies.Comment: 7 pages, 5 figures, uses revtex4; version to appear in Phys.Rev.
Disappearance of the Abrikosov vortex above the deconfining phase transition in SU(2) lattice gauge theory
We calculate the solenoidal magnetic monopole current and electric flux
distributions at finite temperature in the presence of a static quark antiquark
pair. The simulation was performed using SU(2) lattice gauge theory in the
maximal Abelian gauge. We find that the monopole current and electric flux
distributions are quite different below and above the finite temperature
deconfining phase transition point and agree with predictions of the
Ginzburg-Landau effective theory.Comment: 12 pages, Revtex Latex, 6 figures - ps files will be sent upon
reques
Scaling Study of the Leptonic Decay Constants of Heavy-Light Mesons: A Consumers Report on Improvement Factors
A high statistics calculation, performed at and ,
enables us to study the variation of the leptonic decay constants of
heavy pseudoscalar mesons with the lattice spacing . We observe only a weak
dependence when the standard normalization is used for the
quark fields, whereas application of the Kronfeld-Mackenzie normalization
induces a stronger variation with . Increasing the meson mass from
to this situation becomes even more pronounced.Comment: Lattice 93, 3 pages Latex, 2 postscript figures (epsf style
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