Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Penguins with Charm and Quark-Hadron Duality   The integrated branching fraction of the process $B\to X_s l^+l^-$ is
dominated by resonance background from narrow charmonium states, such as $B\to
X_s\psi\to X_s l^+l^-$, which exceeds the non-resonant charm-loop contribution
by two orders of magnitude. The origin of this fact is discussed in view of the
general expectation of quark-hadron duality. The situation in $B\to X_s l^+l^-$
is contrasted with charm-penguin amplitudes in two-body hadronic B decays of
the type $B\to\pi\pi$, for which it is demonstrated that resonance effects and
the potentially non-perturbative $c\bar c$ threshold region do not invalidate
the standard picture of QCD factorization. This holds irrespective of whether
the charm quark is treated as a light or a heavy quark.

5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int