524 research outputs found
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
Semileptonic Decays of D and B Mesons
We report results of our ongoing investigation concerning semileptonic decays
of heavy pseudoscalar mesons into pseudoscalar and vector mesons. Particular
attention is paid to uncertainties in the and the heavy quark mass
dependence of formfactors. Moreover we present a non-perturbative test to the
LMK current renormalization scheme for vector current transition matrix
elements and find remarkable agreement.Comment: 3 pages, uuencoded, contribution to Lat 9
Dual vortices in Abelian projected SU(2) in the Polyakov gauge
We study dual Abrikosov vortices in Abelian projected SU(2) gauge theory in
the Polyakov gauge. We show that vortices are present in this gauge but they
are suppressed with respect to the maximal Abelian gauge. We interpret this
difference in terms of the shielding of the electric charge by the charged
coset fields.Comment: Talk presented at LATTICE96(topology), 3 pages, latex, 4 eps figures,
uses epsfig and espcrc2.sty (included
Semileptonic Decays of Heavy Mesons: A Status Report
We present intermediate results on our ongoing investigation concerning
semileptonic decays of heavy pseudoscalar mesons into pseudoscalar and vector
mesons. The corresponding formfactors are evaluated at several momenta and
appropriate combinations of four light and four heavy quarks, which are chosen
to allow for an extrapolation into the B Meson region. In order to obtain clear
groundstate signals we apply gauge invariant ``Wuppertal'' smearing to the
quarks. The analysis is based on 32 quenched gauge configurations of size at , with Wilson fermions.Comment: 3 pages, uuencoded, contribution to Lat 9
New lattice action for heavy quarks
We extend the Fermilab method for heavy quarks to include interactions of
dimensions 6 and 7 in the action. There are, in general, many new interactions,
but we carry out the calculations needed to match the lattice action to
continuum QCD at the tree level, finding six non-zero couplings. Using the
heavy-quark theory of cutoff effects, we estimate how large the remaining
discretization errors are. We find that our tree-level matching, augmented with
one-loop matching of the dimension-five interactions, can bring these errors
below 1%, at currently available lattice spacings.Comment: 43 pp; v2 conforms with PRD version, improving plots and many minor
thing
Heavy and Light Quarks with Lattice Chiral Fermions
The feasibility of using lattice chiral fermions which are free of
errors for both the heavy and light quarks is examined. The fact that the
effective quark propagators in these fermions have the same form as that in the
continuum with the quark mass being only an additive parameter to a chirally
symmetric antihermitian Dirac operator is highlighted. This implies that there
is no distinction between the heavy and light quarks and no mass dependent
tuning of the action or operators as long as the discretization error is negligible. Using the overlap fermion, we find that the
(and ) errors in the dispersion relations of the pseudoscalar and
vector mesons and the renormalization of the axial-vector current and scalar
density are small. This suggests that the applicable range of may be
extended to with only 5% error, which is a factor of
larger than that of the improved Wilson action. We show that the generalized
Gell-Mann-Oakes-Renner relation with unequal masses can be utilized to
determine the finite errors in the renormalization of the matrix elements
for the heavy-light decay constants and semileptonic decay constants of the B/D
meson.Comment: final version to appear in Int. Jou. Mod. Phys.
Finite ma corrections for sea quark matrix elements
We discuss the finite corrections associated with the computation of sea
quark matrix elements. We find them to differ from the standard normalization
used for valence quarks and to depend strongly on the Lorentz structure of the
current under consideration. Phenomenological implications of these results are
briefly discussed in two examples. We also mention how the magnitude of the
correction factors can be reduced by using a 2-link improved action.Comment: 3 pages, contribution to LATTICE'94, uuencoded compressed tar file
(square root removed in equation (1)
Quark Confinement in the Deconfined Phase
In cylindrical volumes with C-periodic boundary conditions in the long
direction, static quarks are confined even in the gluon plasma phase due to the
presence of interfaces separating the three distinct high-temperature phases.
An effective "string tension" is computed analytically using a dilute gas of
interfaces. At T_c, the deconfined-deconfined interfaces are completely wet by
the confined phase and the high-temperature "string tension" turns into the
usual string tension below T_c. Finite size formulae are derived, which allow
to extract interface and string tensions from the expectation value of a single
Polyakov loop. A cluster algorithm is built for the 3-d three-state Potts model
and an improved estimator for the Polyakov loop is constructed, based on the
number of clusters wrapping around the C-periodic direction of the cluster.Comment: 3 pages, Latex, talk presented at Lattice '97, to appear in Nucl.
Phys. B (Proc. Suppl.), uses espcrc2.st
Application of heavy-quark effective theory to lattice QCD: II. Radiative corrections to heavy-light currents
We apply heavy-quark effective theory to separate long- and short-distance
effects of heavy quarks in lattice gauge theory. In this approach, the inverse
heavy-quark mass and the lattice spacing are treated as short distances, and
their effects are lumped into short-distance coefficients. We show how to use
this formalism to match lattice gauge theory to continuum QCD, order by order
in the heavy-quark expansion. In this paper, we focus on heavy-light currents.
In particular, we obtain one-loop results for the matching factors of lattice
currents, needed for heavy-quark phenomenology, such as the calculation of
heavy-light decay constants, and heavy-to-light transition form factors.
Results for the Brodsky-Lepage-Mackenzie scale are also given.Comment: 32 pages, 8 figures. v2 corrects Eqs. (4.9) and (4.10) and adds a
reference. Program LatHQ2QCD to compute matching one-loop coefficients
available at http://theory.fnal.gov/people/kronfeld/LatHQ2QCD
Quark Confinement Physics in Quantum Chromodynamics
We study abelian dominance and monopole condensation for the quark
confinement physics using the lattice QCD simulations in the MA gauge. These
phenomena are closely related to the dual superconductor picture of the QCD
vacuum, and enable us to construct the dual Ginzburg-Landau (DGL) theory as an
useful effective theory of nonperturbative QCD. We then apply the DGL theory to
the studies of the low-lying hadron structure and the scalar glueball
properties.Comment: Talk given at 15th International Conference on Particle and Nuclei
(PANIC 99), Uppsala, Sweden, 10-16 Jun 1999, 4 page
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