1,333 research outputs found
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
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
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
Heavy-light baryonic mass splittings from the lattice
We present lattice estimates of the mass of the heavy-light baryons
and obtained using propagating heavy quarks. For
our result is GeV, after
extrapolation to the continuum limit and in the quenched approximation.Comment: 3 pages postscript, Contribution to Lattice'9
Virtual Compton Scattering and Generalized Polarizabilities of the Proton
Threshold photon electroproduction off the proton allows one to measure new
electromagnetic observables which generalise the usual polarisabilities. There
are -- a priori -- ten "generalised polarisabilities", functions of the virtual
photon mass. The purpose of this paper is to lay down the appropriate formalism
to extract these quantities from the photon electroproduction cross sections.
We also give a first estimate of the generalised polarisabilities in the non
relativistic quark model.Comment: 45 page postscript file including 2 figures (length just over 1Mb);
also available at
http://www.physics.adelaide.edu.au/theory/papers/ADP-94-25.T165.p
Quenched QCD with domain wall fermions
We report on simulations of quenched QCD using domain wall fermions, where we
focus on basic questions about the formalism and its ability to produce
expected low energy hadronic physics for light quarks. The work reported here
is on quenched lattices at and 5.85, using values
for the length of the fifth dimension between 10 and 48. We report results for
parameter choices which lead to the desired number of flavors, a study of
undamped modes in the extra dimension and hadron masses.Comment: Contribution to Lattice '98. Presented by R. Mawhinney. 3 pages, 3
figure
Nuclear effects in positive pion electroproduction on the deuteron near threshold
Positive pion electroproduction from the deuteron near threshold has been
considered within an approach based on the unitary transformation method. The
gauge independence of the treatment is provided by using an explicitly gauge
independent expression for the reaction amplitude. The results of calculations
for kinematics of the experiments on forward-angle meson
electroproduction accomplished at Saclay and Jefferson Laboratory are discussed
and compared with those given by the impulse approximation. It is shown that
the observed behaviour of the cross sections is in accordance with the
calculations based on the pion-nucleon dynamics. In particular, the pion
production rate suppression in the reaction compared to that
for the one can be due to such ``nuclear medium'' effects as
nucleon motion and binding along with Pauli blocking in the final state.Comment: 15 pages, 8 figure
The Leptonic Decay Constants of Mesons and the Lattice Resolution
We present a high statistics study of the leptonic decay constant of
heavy pseudoscalar mesons using propagating heavy Wilson quarks within the
quenched approximation, on lattices covering sizes from about 0.7~fm to 2~fm.
Varying between 5.74 and 6.26 we observe a sizeable dependence of
when one uses the quark field normalization that was suggested by
Kronfeld and Mackenzie, compared with the weaker dependence observed for the
standard relativistic norm. The two schemes come into agreement when one
extrapolates to . The extrapolations needed to reach the
continuum quantity introduce large errors and lead to the value
~GeV in the quenched approximation. This suggests that much more
effort will be needed to obtain an accurate lattice prediction for .Comment: 11 pages Latex + 5 tables + 8 postscript figures, unix shell archive,
DESY preprint DESY 93-17
Quantum Corrections to Baryon Properties in Chiral Soliton Models
We present a procedure to calculate 1-loop graphs in the soliton sector of
chiral Lagrangians and use it to calculate quantum corrections to certain
baryon observables in Skyrme-type models. Results generally show an improvement
over the values obtained in tree approximation except for the case of the axial
coupling g_A.Comment: Chapters on magnetic polarizabilities and e.m. properties of Delta
isobar added, 90 pages, Latex, 9 Postscript figure
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