Hard exclusive neutrino production of a light meson

We update the leading order in $\alpha_s$ QCD amplitude for deep exclusive neutrino and antineutrino production of a light meson on an unpolarized nucleon. The factorization theorems of the collinear QCD approach allow us to write the amplitude as the convolution of generalized parton distributions (GPDs) and perturbatively calculable coefficient functions. We study both the pseudoscalar meson and longitudinally polarized vector meson cases. It turns out that, contrarily to the electroproduction case, the leading twist scattering amplitudes for $\pi$ and $\rho_L$ productions are proportional to one another, which may serve as an interesting new test of the leading twist dominance of exclusive processes at medium scale. The dominance of the gluonic contribution to most cross sections is stressed.