Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurement of the gamma gamma* --> pi0 transition form factor   We study the reaction e+e- --> e+e-pi0 and measure the gamma gamma* --> pi0
transition form factor in the momentum transfer range from 4 to 40 GeV^2. The
analysis is based on 442 fb^-1 of integrated luminosity collected at PEP-II
with the BABAR detector at e+e- center-of-mass energies near 10.6 GeV.

30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol