Generalized parton distributions from neutrino experiments

Abstract

The analysis of deeply virtual meson production is extended to neutrino-production of the pseudo-Goldstone mesons (pions, kaons, eta-mesons) on nucleons, with the flavor content of the recoil baryon either preserved, or changed to a hyperon from the same SU(3) octet. We rely on the SU(3) relations and express all the cross-sections in terms of the proton generalized parton distributions (GPDs). The corresponding amplitudes are calculated at the leading twist level and in the leading order in \alpha_{s}, using a phenomenological parametrization of GPDs. We also included in the analysis the electromagnetic O(alpha_{em})-corrections to neutrino-induced deeply virtual meson production (\nuDVMP). We found that such electromagnetic corrections decrease with Q^2 in the Bjorken regime less than the standard \nuDVMP handbag contribution, so the electromagnetic mechanism dominates at large Q^2. The electromagnetic corrections give rise to an angular correlation between the lepton and hadron scattering planes with harmonics sensitive to the real and imaginary parts of the DVMP amplitude. These corrections constitute a few percent effect in the kinematics of the forthcoming MINERvA experiment at Fermilab and should be taken into account in precise tests of GPD parametrizations. For virtualities Q^2~100 GeV^2 these corrections become on a par with \nuDVMP handbag contributions.