3,407 research outputs found
Binding Energies in Nonrelativistic Field Theories
Relativistic corrections communicate the binding energy of a bound state to
its kinetic mass. This mechanism is reviewed and used to explain anomalous
results of Collins, Edwards, Heller, and Sloan (hep-lat/9512026), which
compared rest and kinetic masses of heavy-light mesons and quarkonia.Comment: 4 pages, 1 figure, poster presented at LATTICE96(heavy quarks
F_B from moving B mesons
We show results for the B meson decay constant calculated both for B mesons
at rest and those with non-zero momentum and using both the temporal and
spatial components of the axial vector current. It is an important check of
lattice systematic errors that all these determinations of f_B should agree. We
also describe how well different smearings for the B meson work at non-zero
momentum - the optimal smearing has a narrow smearing for the b quark.Comment: Lattice2001(heavyquark
Flavor-Symmetry Restoration and Symanzik Improvement for Staggered Quarks
We resolve contradictions in the literature concerning the origins and size
of unphysical flavor-changing strong interactions generated by the
staggered-quark discretization of QCD. We show that the leading contributions
are tree-level in \order(a^2) and that they can be removed by adding three
correction terms to the link operator in the standard action. These corrections
are part of the systematic Symanzik improvement of the staggered-quark action.
We present a new improved action for staggered quarks that is accurate up to
errors of \order(a^4,a^2\alpha_s) --- more accurate than most, if not all,
other discretizations of light-quark dynamics.Comment: 7 page
Semileptonic B Decays from an NRQCD/D234 Action
Semileptonic B decays are studied on quenched anisotropic lattices using
Symanzik improved glue, NRQCD heavy quark and D234 light quark actions. We
employ constrained fits to extract ground state contributions to two- and
three-point correlators. Results for the B --> pi, l nubar decay form factors
are compared with previous lattice results. We find that our systematic errors
(excluding quenching errors) are dominated by chiral extrapolation
uncertainties.Comment: Lattice2002(Heavy quark physics
P-wave meson properties with Wilson quarks
We describe two calculations involving P-wave mesons made of Wilson quarks:
the strong coupling constant in the presence of two flavors of light
dynamical fermions and the mass and decay constant of the meson.Comment: Poster presented at Lattice '94, September 27--October 1, 1994,
Bielefeld, Germany (no changes to manuscript, but correction of Authors list
above
Pion Form Factor in the Factorization Formalism
Based on the light-cone (LC) framework and the factorization formalism,
the transverse momentum effects and the different helicity components'
contributions to the pion form factor are recalculated. In
particular, the contribution to the pion form factor from the higher helicity
components (), which come from the spin-space Wigner
rotation, are analyzed in the soft and hard energy regions respectively. Our
results show that the right power behavior of the hard contribution from the
higher helicity components can only be obtained by fully keeping the
dependence in the hard amplitude, and that the dependence in LC wave
function affects the hard and soft contributions substantially. As an example,
we employ a model LC wave function to calculate the pion form factor and then
compare the numerical predictions with the experimental data. It is shown that
the soft contribution is less important at the intermediate energy region.Comment: 21 pages, 4 figure
Improved Currents for Heavy Quarks
We discuss lattice artifacts for matrix elements of hadrons containing one or
more heavy quark. In particular, we analyze interrelations between lattice
artifacts and the expansion. The implications for calculations of
heavy-light decay constants and of semi-leptonic form factors are discussed.Comment: 3 pages, no figures, uuencoded PostScript, proceedings of Lattice
'94. LaTeX at ftp://fnth06.fnal.gov/pub/Fermilab-Pub/95.00
Improved Nonrelativistic QCD for Heavy Quark Physics
We construct an improved version of nonrelativistic QCD for use in lattice
simulations of heavy quark physics, with the goal of reducing systematic errors
from all sources to below 10\%. We develop power counting rules to assess the
importance of the various operators in the action and compute all leading order
corrections required by relativity and finite lattice spacing. We discuss
radiative corrections to tree level coupling constants, presenting a procedure
that effectively resums the largest such corrections to all orders in
perturbation theory. Finally, we comment on the size of nonperturbative
contributions to the coupling constants.Comment: 40 pages, 2 figures (not included), in LaTe
QCD corrections to e+ e- --> 4 jets
We report on the next-to-leading order QCD calculation for e+ e- --> 4 jets.
We explain some modern techniques which have been used to calculate the
one-loop amplitudes efficiently. We further report on the general purpose
numerical program ``Mercutio'', which can be used to calculate any infrared
safe four-jet quantity in electron-positron annihilation at next-to-leading
order.Comment: 4 pages, talk given at the UK Phenomenology Workshop on Collider
Physics, Durham, 19-24 September 199
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