271 research outputs found
Non-factorizable contributions to
It is pointed out that decays of the type have no
factorizable contributions, unless at least one of the charmed mesons in the
final state is a vector meson. The dominant contributions to the decay
amplitudes arise from chiral loop contributions and tree level amplitudes
generated by soft gluon emissions forming a gluon condensate. We predict that
the branching ratios for the processes ,
and are all of
order , while has a
branching ratio 5 to 10 times bigger. We emphasize that the branching ratios
are sensitive to corrections.Comment: 4 pages, 4 figures. Based on talk by J.O. Eeg at BEACH 2004, 6th
international conference on Hyperons, Charm and Beauty Hadrons, Illionois
Institute of Technology, Chicago, june. 27 - july 3, 200
The \beta-term for D^* --> D \gamma within a heavy-light chiral quark model
We present a calculation of the \beta-term for D^* --> D gamma within a
heavy-light chiral quark model. Within the model, soft gluon effects in terms
of the gluon condensate with lowest dimension are included. Also, calculations
of 1/m_c corrections are performed. We find that the value of \beta is rather
sensitive to the constituent quark mass compared to other quantities calculated
within the same model. Also, to obtain a value close to the experimental value,
one has to choose a constituent light quark mass larger than for other
quantities studied in previous papers. For a light quark mass in the range 250
to 300 MeV and a quark condensate in the range -(250-270 MeV)^3 we find the
value (2.5 +- 0.6) GeV^-1. This value is in agreement with the value of \beta
extracted from experiment 2.7 +- 0.2 GeV^-1.Comment: 16 pages, 5 figure
Chiral quark models and their applications
We give an overview of chiral quark models, both for the pure light sector
and the heavy-light sector.
We describe how such models can be bosonized to obtain welWe give an overview
of chiral quark models, both for the pure light sector and the heavy-light
sector.
We describe how such models can be bosonized to obtain well known chiral
Lagrangians which can be inferred from the symmetries of QCD alone. In
addition, we can within these models calculate the coefficients of the various
pieces of the chiral Lagrangians. We discuss a few applications of the models,
in particular, \bbar mixing and processes of the type ,
where might be both pseudoscalar and vector. We suggest how the formalism
might be extended to include light vectors (), and heavy to
light transitions like . l known chiral Lagrangians which can be
inferred from the symmetries of QCD alone. In addition, we can within these
models calculate the coefficients of the various pieces of the chiral
Lagrangians. We discuss a few applications of the models, in particular,
\bbar mixing and processes of the type , where might be
both pseudoscalar and vector. We suggest how the formalism might be extended to
include light vectors (), and heavy to light transitions like
.Comment: 37 pages, 16 figures. Dedicated to the memory of Prof. D. Tadic,
Submitted to Fizika B, Zagre
Non-factorizable effects in B-anti-B mixing
We study the B-parameter (``bag factor'') for B-anti-B mixing within a
recently developed heavy-light chiral quark model. Non-factorizable
contributions in terms of gluon condensates and chiral corrections are
calculated. In addition, we also consider 1/m_Q corrections within heavy quark
effective field theory. Perturbative QCD effects below \mu = m_b known from
other work are also included. Considering two sets of input parameters, we find
that the renormalization invariant B-parameter is B = 1.51 +- 0.09 for B_d and
B = 1.40 +- 0.16 for B_s.Comment: 23 pages, 7 figures, RevTex 4 Small changes, included more details in
the tex
Color suppressed contributions to the decay modes B_{d,s} -> D_{s,d} D_{s,d}, B_{d,s} -> D_{s,d} D^*_{s,d}, and B_{d,s} -> D^*_{s,d} D^*_{s,d}
The amplitudes for decays of the type , have no
factorizable contributions, while , and have relatively small factorizable contributions
through the annihilation mechanism. The dominant contributions to the decay
amplitudes arise from chiral loop contributions and tree level amplitudes which
can be obtained in terms of soft gluon emissions forming a gluon condensate. We
predict that the branching ratios for the processes ,
and are all
of order , while ,
and are of
order . We obtain branching ratios for two 's in
the final state of order two times bigger.Comment: 15 pages, 4 figure
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