Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Heavy flavours from QCD spectral sum rules   We present a summary update of the QCD spectral sum rule (QSSR) results for
the running and {\it perturbative pole} quark masses, the $f_D$ and $f_B$
leptonic decay constants, the heavy-to-light and heavy-to-heavy exclusive
transition-form factors. Analytic expressions of these latter quantities are
presented, which give a deeper understanding of their $q^2$- and infinite
mass-behaviours. A short comparison of the QSSR results with alternative
approaches is done.

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The categories of this paper are: math-ph
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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: nucl-th
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The categories of this paper are: hep-th
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The categories of this paper are: ao-sci
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The categories of this paper are: cs
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The categories of this paper are: patt-sol
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The categories of this paper are: dg-ga
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The categories of this paper are: math
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The categories of this paper are: gr-qc
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The categories of this paper are: econ
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The categories of this paper are: q-bio
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The categories of this paper are: adap-org
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The categories of this paper are: eess
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The categories of this paper are: bayes-an