Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quark structure of the pion and pion form factor   We consider the pion structure in the region of low and moderately high
momentum transfers: at low $Q^2$, the pion is treated as a composite system of
constituent quarks; at moderately high momentum transfers,
$Q^2=10\div25\;GeV^2$, the pion \ff is calculated within perturbative QCD
taking into account one--gluon hard exchange. Using the data on pion \ff at
$Q^2<3\;GeV^2$ and pion axial--vector decay constant, we reconstruct the pion
\wf in the soft and intermediate regions. This very wave function combined with
one--gluon hard scattering amplitude allows a calculation of the pion \ff in
the hard region $Q^2=10\div25\;GeV^2$. A specific feature of the reconstructed
pion \wf is a quasi--zone character of the $q\bar q$--excitations. On the basis
of the obtained pion \wf and the data on deep inelastic scattering off the
pion, the valence quark distribution in a constituent quark is determined.

17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat