665 research outputs found
Updates of effects on CP angles determination in B decays
The recently observed CP violation in B decay and -\ovar{B} mixing data
put constraints on the mass of and the parameters of the right-handed
current quark mixing matrix in gauge
model. It is shown that the allowed region of parameters are severely
restricted for light with mass on the order of 1 TeV. There exist sets of
parameters which can accommodate large CP violation as measured by Belle,
, for TeV.Comment: 11pages, 19 figures, LaTeX2
Study of color suppressed modes
The color suppressed modes are
analyzed in perturbative QCD approach. We find that the dominant contribution
is from the non-factorizable diagrams. The branching ratios calculated in our
approach for agree with current experiments. By
neglecting the gluonic contribution, we predict the branching ratios of are at the comparable size of , but smaller than that of .Comment: revtex, 5 pages, axodraw.st
Study of decays
We investigate the production of the novel -wave mesons and
, identified as and , in heavy
meson decays, respectively. With the heavy quark limit, we give our modelling
wave functions for the scalar meson . Based on the assumptions of
color transparency and factorization theorem, we estimate the branching ratios
of decays in terms of the obtained wave functions. Some
remarks on productions are also presented.Comment: 16 pages, 2 figures, Revtex4, to be published in Phys. Rev.
Nonfactorizable contributions to decays
While the factorization assumption works well for many two-body nonleptonic
meson decay modes, the recent measurement of with
, and shows large deviation from this assumption. We
analyze the decays in the perturbative QCD approach based on
factorization theorem, in which both factorizable and nonfactorizable
contributions can be calculated in the same framework. Our predictions for the
Bauer-Stech-Wirbel parameters, and and and , are
consistent with the observed and branching ratios,
respectively. It is found that the large magnitude and the large
relative phase between and come from color-suppressed
nonfactorizable amplitudes. Our predictions for the , branching ratios can be confronted with
future experimental data.Comment: 25 pages with Latex, axodraw.sty, 6 figures and 5 tables, Version
published in PRD, Added new section 5 and reference
factorization of exclusive processes
We prove factorization theorem in perturbative QCD (PQCD) for exclusive
processes by considering and . The relevant form factors are expressed as the convolution of hard
amplitudes with two-parton meson wave functions in the impact parameter
space, being conjugate to the parton transverse momenta . The point is
that on-shell valence partons carry longitudinal momenta initially, and acquire
through collinear gluon exchanges. The -dependent two-parton wave
functions with an appropriate path for the Wilson links are gauge-invariant.
The hard amplitudes, defined as the difference between the parton-level
diagrams of on-shell external particles and their collinear approximation, are
also gauge-invariant. We compare the predictions for two-body nonleptonic
meson decays derived from factorization (the PQCD approach) and from
collinear factorization (the QCD factorization approach).Comment: 11 pages, REVTEX, 5 figure
Semileptonic decays in the light-cone QCD sum rules
Semileptonic () decays are investigated systematically in the
light-cone QCD sum rules. Special emphasis is put on the LCSR calculation on
weak form factors with an adequate chiral current correlator, which turns out
to be particularly effective to control the pollution by higher twist
components of spectator mesons. The result for each channel depends on the
distribution amplitude of the the producing meson. The leading twist
distribution amplitudes of the related heavy mesons and charmonium are worked
out by a model approach in the reasonable way. A practical scenario is
suggested to understand the behavior of weak form factors in the whole
kinematically accessible ranges. The decay widths and branching ratios are
estimated for several () decay modes of current interest.Comment: 8 pages, talk given by the first arthur at 4th International
Conference on Flavor Physics (ICFP 2007), Beijing, China, Sept 24-28, 200
Threshold resummation for exclusive B meson decays
We argue that double logarithmic corrections need to be
resumed in perturbative QCD factorization theorem for exclusive meson
decays, when the end-point region with a momentum fraction is
important. These double logarithms, being of the collinear origin, are absorbed
into a quark jet function, which is defined by a matrix element of a quark
field attached by a Wilson line. The factorization of the jet function from the
decay is proved to all orders. Threshold resummation for
the jet function leads to a universal, {\it i.e.}, process-independent, Sudakov
factor, whose qualitative behavior is analyzed and found to smear the end-point
singularities in heavy-to-light transition form factors.Comment: 10 pages, more details are include
Revisiting the B {\to} {\pi} {\rho}, {\pi} {\omega} Decays in the Perturbative QCD Approach Beyond the Leading Order
We calculate the branching ratios and CP asymmetries of the ,
decays in the perturbative QCD factorization approach up to the
next-to-leading-order contributions. We find that the next-to-leading-order
contributions can interfere with the leading-order part constructively or
destructively for different decay modes. Our numerical results have a much
better agreement with current available data than previous leading-order
calculations, e.g., the next-to-leading-order corrections enhance the
branching ratios by a factor 2.5, which is helpful
to narrow the gaps between theoretic predictions and experimental data. We also
update the direct CP-violation parameters, the mixing-induced CP-violation
parameters of these modes, which show a better agreement with experimental data
than many of the other approaches.Comment: 23 pages, 4 figures, 4 table
Perturbative QCD analysis of decays
We study the first observed charmless modes, the
decays, in perturbative QCD formalism. The obtained branching ratios
are larger than
from QCD factorization. The comparison of the predicted magnitudes and phases
of the different helicity amplitudes, and branching ratios with experimental
data can test the power counting rules, the evaluation of annihilation
contributions, and the mechanism of dynamical penguin enhancement in
perturbative QCD, respectively.Comment: 14 pages, 2 tables, brief disscussion on hard sacle added, version to
appear in PR
Branching ratios of decays in perturbative QCD approach
We study the rare decays , which can occur only via
annihilation type diagrams in the standard model. We calculate all of the four
modes, , in the framework of perturbative QCD approach
and give the branching ratios of the order about .Comment: 18 pages, 1 figure, Revte
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