355 research outputs found
Decays of Heavy Mesons
We present preliminary results for heavy to light transitions of pseudoscalar
mesons, induced by the vector and tensor operators. This lattice study is
performed in quenched approximation, by using the nonperturbatively improved
Wilson action and operators. We also update the values of the heavy-light meson
decay constants.Comment: LATT99(Heavy Quarks), 3 pages, 2 figure
Perturbative renormalization for static and domain-wall bilinears and four-fermion operators with improved gauge actions
We calculate one-loop renormalization factors for heavy-light bilinears as
well as four-fermion operators relevant for mixing
calculations on the lattice. We use the static approximation for heavy quarks
and the domain-wall formulation for light quarks. We present results for
different choices of improved gauge action.Comment: 21 pages, 3 figures, 3 tables, revtex
Heavy --> Light semileptonic decays of pseudoscalar mesons from lattice QCD
We have computed the form factors for B --> pi and D --> K(pi) semileptonic
decays on the lattice by using full non-perturbative O(a) improvement, in the
quenched approximation. Our results are expressed in terms of few parameters
which describe the q^2-dependence and normalization of the form factors.Comment: 28 pages (LaTeX2e), 11 PostScript figures (version to appear in
Nucl.Phys.B
Power Corrections to Perturbative QCD and OPE in Gluon Green Functions
We show that QCD Green functions in Landau Gauge exhibit sizable
corrections to the expected perturbative behavior at energies as high as 10
GeV. We argue that these are due to a -condensate which does not vanish
in Landau gauge.Comment: 3 pages 1 figure lattice2001 (gaugetheories
Non-perturbative scale evolution of four-fermion operators
We apply the Schroedinger Functional (SF) formalism to determine the
renormalisation group running of four-fermion operators which appear in the
effective weak Hamiltonian of the Standard Model. Our calculations are done
using Wilson fermions and the parity-odd components of the operators.
Preliminary results are presented for the operator .Comment: Lattice2002(improve
Masses and decay constants of mesons with twisted mass fermions
We present a preliminary lattice determination of the masses and decay
constants of the pseudoscalar and vector mesons and . Our analysis
is based on the gauge configurations produced by the European Twisted Mass
Collaboration with flavors of dynamical quarks. We simulated
at three different values of the lattice spacing and with pion masses as small
as 210 MeV. Heavy-quark masses are simulated directly on the lattice up to
times the physical charm mass. The physical b-quark mass is reached
using the ETMC ratio method. Our preliminary results are: MeV, MeV, and .Comment: 7 pages, 3 figures, 1 table; contribution to the proceedings of the
XXXVI Int'l Workshop on Lattice Field Theory (LATTICE2018), July 22-28, 2018,
East Lansing, Michigan State University (Michigan, USA
D-meson decay constants and a check of factorization in non-leptonic B-decays
We compute the vector meson decay constants fD*, fDs* from the simulation of
twisted mass QCD on the lattice with Nf = 2 dynamical quarks. When combining
their values with the pseudoscalar D(s)-meson decay constants, we were able (i)
to show that the heavy quark spin symmetry breaking effects with the charm
quark are large, fDs*/fDs = 1.26(3), and (ii) to check the factorization
approximation in a few specific B-meson non-leptonic decay modes. Besides our
main results, fD* = 278 \pm 13 \pm 10 MeV, and fDs* = 311 \pm 9 MeV, other
phenomenologically interesting results of this paper are: fDs*/fD* = 1.16 \pm
0.02 \pm 0.06, fDs*/fD = 1.46 \pm 0.05 \pm 0.06, and fDs/fD* = 0.89 \pm 0.02
\pm 0.03. Finally, we correct the value for B(B0 \rightarrow D+ pi-) quoted by
PDG, and find B(B0 \rightarrow D+ pi-) = (7.8 \pm 1.4) \times 10-7.
Alternatively, by using the ratios discussed in this paper, we obtain B(B0
\rightarrow D+ pi-) = (8.3 \pm 1.0 \pm 0.8)\times10-7.Comment: 16 pages, 4 eps figure
A Theoretical Prediction of the Bs-Meson Lifetime Difference
We present the results of a quenched lattice calculation of the operator
matrix elements relevant for predicting the Bs width difference. Our main
result is (\Delta\Gamma_Bs/\Gamma_Bs)= (4.7 +/- 1.5 +/- 1.6) 10^(-2), obtained
from the ratio of matrix elements, R(m_b)=/<\bar
B_s^0|Q_L|B_s^0>=-0.93(3)^(+0.00)_(-0.01). R(m_b) was evaluated from the two
relevant B-parameters, B_S^{MSbar}(m_b)=0.86(2)^(+0.02)_(-0.03) and
B_Bs^{MSbar}(m_b) = 0.91(3)^(+0.00)_(-0.06), which we computed in our
simulation.Comment: 21 pages, 7 PostScript figure
Possible explanation of the discrepancy of the light-cone QCD sum rule calculation of g(D*Dpi) coupling with experiment
The introduction of an explicit negative radial excitation contribution in
the hadronic side of the light cone QCD sum rule (LCSR) of Belyaev, Braun,
Khodjamirian and Ruckl, can explain the large experimental value of g(D*Dpi),
recently measured by CLEO. At the same time, it considerably improves the
stability of the sum rule when varying the Borel parameter.Comment: 9 pages, 1 PostScript figure
- âŠ