Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The hard scattering amplitude for the higher helicity components of the
  pion form factor   For obtaining the spin space wave function of the pion meson in the
light-cone formalism from the naive quark model, it is necessary to take into
account Wigner rotation. Consequently there are higher helicity
($\lambda_1+\lambda_2=\pm 1$) components in the light-cone spin space wave
function of the pion besides the usual helicity ($\lambda_1+\lambda_2=0$)
components. For the pion electromagnetic form factor, we calculate the
hard-scattering amplitude for the higher helicity components in the light-cone
perturbation theory. It is found that the hard-scattering amplitude for the
higher helicity components is of order $1/Q^4$, which is vanishingly small
compared to that of the ordinary helicity component at very high $Q^2$ but
should be considered in the $Q^2$ region where experimental data are available.

31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
4
The categories of this paper are: cond-mat