4,062 research outputs found
K_l3 form factor with two-flavors of dynamical domain-wall quarks
We report on our calculation of K \to \pi vector form factor by numerical
simulations of two-flavor QCD on a 16^3x32x12 lattice at a \simeq 0.12 fm using
domain-wall quarks and DBW2 glue. Our preliminary result at a single sea quark
mass correponding to m_PS/m_V \simeq 0.53 shows a good agreement with previous
estimate in quenched QCD and that from a phenomenological model.Comment: 6 pages, 5 figures, poster presented at Lattice2005 (Weak matrix
elements); v2: a reference adde
SU(3) Flavor Breaking in Hadronic Matrix Elements for Oscillations
We present an analysis, using quenched configurations at 5.7, 5.85,
6.0, and 6.3 of the matrix element \MP\equiv\langle \bar P_{hl}|\bar h
\gamma_\mu (1-\gamma_5)l \bar h \gamma_\mu(1-\gamma_5)l|P_{hl}\rangle for
heavy-light pseudoscalar mesons. The results are extrapolated to the physical
meson states, \Bd and \Bs. We directly compute the ratio \MS/\MB, and
obtain the preliminary result \MS/\MB=1.54(13)(32). A precise value of this
SU(3) breaking ratio is important for determining once the mixing
parameter for \Bs-\bar\Bs is measured experimentally. We also determine
values for the corresponding B parameters, , which we cannot distinguish in the present analysis.Comment: Poster presented at LATTICE96(heavy quarks). LaTeX, uses espcrc2.sty
and epsf, 4 pages, 4 postscript figures include
Semi-inclusive hadronic B decays as null tests of the Standard Model
We propose a new set of observables that can be used as experimental null
tests of the Standard Model in charged and neutral B decays. The CP asymmetries
in hadronic decays of charged B mesons into inclusive final states containing
at least one of the following mesons: K_{S,L}, eta', c\bar c bound states or
neutral K^* or D mesons, for all of which a U-spin rotation is equivalent to a
CP conjugation, are CKM suppressed and furthermore vanish in the exact U-spin
limit. We show how this reduces the theoretical error by using Soft Collinear
Effective Theory to calculate the CP asymmetries for K_{S,L} X_{s+d}, K^*
X_{s+d} and eta' X_{s+d} final states in the endpoint region. For these CP
asymmetries only the flavor and not the charge of the decaying B meson needs to
be tagged up to corrections of NLO in 1/m_b, making the measurements more
accessible experimentally.Comment: 8 pages, significantly expanded after the observation that both
neutral and charged B decays can be used, calculation for decays involving
eta' adde
Calculation of the neutron electric dipole moment with two dynamical flavors of domain wall fermions
We present a study of the neutron electric dipole moment () within
the framework of lattice QCD with two flavors of dynamical lig ht quarks. The
dipole moment is sensitive to the topological structure of the gaug e fields,
and accuracy can only be achieved by using dynamical, or sea quark, calc
ulations. However, the topological charge evolves slowly in these calculations,
le ading to a relatively large uncertainty in . It is shown, using
quenched configurations, that a better sampling of the charge d istribution
reduces this problem, but because the CP even part of the fermion determinant
is absent, both the topological charge dis tribution and are
pathological in the chiral limit. We discuss the statistical and systematic
uncertainties arising from the topological charge distr ibution and unphysical
size of the quark mass in our calculations and prospects fo r eliminating them.
Our calculations employ the RBC collaboration two flavor domain wall fermion
and DBW2 gauge action lattices with inverse lattice spacing 1.7
GeV, physical volume fm), and light quark mass roughly equal
to the strange quark mass ( and 0.04). We determine a value of
the electric dipole moment that is zero withi n (statistical) errors, e--fm at the smaller sea quark mass. Satisfactory
results for the magnetic and electric form factors of the proton and neutron
are also obtained and presented.Comment: 46 pages. Changed one author addres
Lattice QCD with domain wall quarks and applications to weak matrix elements
Using domain wall fermions, we estimate in
quenched QCD which is consistent with previous calculations. At \gbeta=6.0
and 5.85 we find the ratio in agreement with the experimental
value, within errors. These results support expectations that errors are
exponentially suppressed in low energy () observables, and
indicate that domain wall fermions have good scaling behavior at relatively
strong couplings. We also demonstrate that the axial current numerically
satisfies the lattice analog of the usual continuum axial Ward identity.Comment: Contribution to Lattice '97. 3 pages, 2 epsf figure
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