Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quark-Hadron Duality in the 't Hooft Model for Meson Weak Decays:
  Different Quark Diagram Topologies   We compare the effects of different quark diagram topologies on the weak
hadronic width of heavy-light mesons in the large N_c limit. We enumerate the
various topologies and show that the only one dominant (or even comparable) in
powers of N_c to the noninteracting spectator "tree" diagram is the
"annihilation" diagram, in which the valence quark-antiquark pair annihilate
weakly. We compute the amplitude for this diagram in the 't Hooft model (QCD in
1+1 spacetime dimensions with a large number of colors N_c) at the hadronic
level and compare to the Born term partonic level. We find that quark-hadron
duality is not well satisfied, even after the application of a smearing
procedure to the hadronic result. A number of interesting subtleties absent
from the tree diagram case arise in the annihilation diagram case, and are
described in detail.

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The categories of this paper are: cs
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
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The categories of this paper are: econ
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The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
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The categories of this paper are: physics
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The categories of this paper are: acc-phys
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The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
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The categories of this paper are: nlin
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The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph