12 research outputs found
An Investigation of the Soft Pion Relation in Quenched Lattice QCD
A lattice determination of the form factor and decay constants for the
semileptonic decay of heavy pseudoscalar (PS) mesons at zero recoil is
presented from which the soft pion relation is satisfied. Chiral extrapolation
of the form factor is performed at constant . Pole dominance is used to
extrapolate the form factor in heavy quark mass. At the B mass, the form factor
at zero recoil lies somewhat below the ratio of decay constants; the relation
remains satisfied within error.Comment: 3 pages, 2 figure
The eta' meson from lattice QCD
We study the flavour singlet pseudoscalar mesons from first principles using
lattice QCD. With N_f=2 flavours of light quark, this is the so-called eta_2
meson and we discuss the phenomenological status of this. Using maximally
twisted-mass lattice QCD, we extract the mass of the eta_2 meson at two values
of the lattice spacing for lighter quarks than previously discussed in the
literature. We are able to estimate the mass value in the limit of light quarks
with their physical masses.Comment: 16 pages: version accepted for publicatio
Chiral Lagrangian Parameters for Scalar and Pseudoscalar Mesons
The results of a high-statistics study of scalar and pseudoscalar meson
propagators in quenched lattice QCD are presented. For two values of lattice
spacing, ( fm) and 5.9 ( fm), we
probe the light quark mass region using clover improved Wilson fermions with
the MQA pole-shifting ansatz to treat the exceptional configuration problem.
The quenched chiral loop parameters and are determined
from a study of the pseudoscalar hairpin correlator. From a global fit to the
meson correlators, estimates are obtained for the relevant chiral Lagrangian
parameters, including the Leutwyler parameters and . Using the
parameters obtained from the singlet and nonsinglet pseudoscalar correlators,
the quenched chiral loop effect in the nonsinglet scalar meson correlator is
studied. By removing this QCL effect from the lattice correlator, we obtain the
mass and decay constant of the ground state scalar, isovector meson .Comment: 36 pages, 12 figures, LaTe
Two flavors of dynamical quarks on anisotropic lattices
We report on our study of two-flavor full QCD on anisotropic lattices using
-improved Wilson quarks coupled with an RG-improved glue. The bare gauge
and quark anisotropies corresponding to the renormalized anisotropy
are determined as functions of and , which
covers the region of spatial lattice spacings --0.16 fm and
--0.9. The calibrations of the bare anisotropies are
performed with the Wilson loop and the meson dispersion relation at 4 lattice
cutoffs and 5--6 quark masses. Using the calibration results we calculate the
meson mass spectrum and the Sommer scale . We confirm that the values of
calculated for the calibration using pseudo scalar and vector meson
energy momentum dispersion relation coincide in the continuum limit within
errors. This work serves to lay ground toward studies of heavy quark systems
and thermodynamics of QCD including the extraction of the equation of state in
the continuum limit using Wilson-type quark actions.Comment: 16 pages, 23 figures, Version accepted for publication in Physical
Review
Results for the Etaprime Mass from Two-Flavor Lattice QCD
We present results for the mass of the etaprime meson for two-flavor lattice
QCD in the continuum limit, calculated on the CP-PACS computer, using an
RG-improved gauge action and clover fermion action with tadpole-improved csw.
Measurements are made at three couplings corresponding to a approx. 0.22, 0.16,
0.11 fm for four quark masses corresponding to mpi over mrho approx. 0.8, 0.75,
0.7, 0.6. Thw two-loop diagrams are evaluated using a noisy source method.
Quark smearing for both one- and two- loop diagrams is successfully applied to
obtain ground state signals in the etaprime channel. We obtain
metaprime=0.960(87)+0.036-0.286GeV in the continuum limit, where the second
error represents the systematic uncertainty coming from varying the functional
form for chiral and continuum extrapolations.Comment: 3 pages, 6 figure
Heavy-light hadron matrix elements from lattice QCD
SIGLEAvailable from British Library Document Supply Centre-DSC:DXN037326 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Decay constants of B and D mesons from non-perturbatively improved lattice QCD
The decay constants of B, D and K mesons are computed in quenched lattice QCD at two different values of the coupling. The action and operators are improved with non-perturbative coefficients. The results are fB=195(6)+24?23 MeV, fD=206(4)+17?10 MeV, fBs=220(6)+23?28 MeV, fDs=229(3)+23?12 MeV and fK=150(3)+12?8 MeV. Systematic errors are discussed in detail. Results for vector decay constants, flavour symmetry breaking ratios of decay constants, the pseudoscalar-vector mass splitting and D meson masses are also presented