Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the pion distribution amplitude. Derivation, properties, predictions   We provide an in-depth analysis of the $\pi$ distribution amplitude in terms
of two different Gegenbauer representations. Detailed predictions for the
$\pi-\gamma$ transition form factor are presented, obtained with light-cone sum
rules. Various $\pi$ distribution amplitudes are tested and the crucial role of
their endpoint behavior in the form-factor analysis is discussed. Comparison
with the data is given.

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The categories of this paper are: hep-th
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The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
3
The categories of this paper are: physics