Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: W-exchange and W-annihilation processes of B mesons   Using the PQCD method we calculate the W-exchange and the W-annihilation
processes of B mesons, which in general involve a charm quark or anti-quark in
the final state. The nonvanishing amplitudes of these processes are found to be
suppressed by a factor of $m_c/m_b$ compared to the tree or the time-like
penguin processes, but some of them are within the reach of observation at the
future B-factories, and $\bar B_d^0 \to D^+_s K^-$ whose branching ratio is
found to be $6.6 \times 10^{-6}$ can be found even before the B-factory era.
Comparisons with the results based on the BSW model are also given.

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The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
2
The categories of this paper are: math
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org
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The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
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The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga