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 the Wigner rotation. Consequently there are higher helicity (λ1+λ2=±1) components in the light-cone spin space wave function of pion in addition to the usual helicity (λ1+λ2=0) components. For the pion electromagnetic form factor, we calculate the hard-scattering amplitude for the higher helicity components in light-cone perturbation theory. It is found that the hard-scattering amplitude for the higher helicity components is of order 1/Q4, which is vanishingly small compared to that of the ordinary helicity components at very high Q2 but should be considered in the Q2 region where experimental data are available. copyright 1997 The American Physical Society