The kinematics of the process ℓN → ℓNV, is studied in the one-photon approximation for unpolarized as well as polarized leptons ℓ. The vector-meson spin density matrix is expressed in terms of the s-channel helicity amplitudes in the hadron c.m.s. and the vector-meson decay angular distribution is discussed. The use of longitudinally polarized lepton beams is found to increase considerably the amount of information that can be deduced from the decay distribution. With longitudinal beam polarization it is possible to separate all 26 observable independent density matrix elements into contributions from natural and unnatural parity exchange in the t-channel, respectively. © 1973.
Schilling, K., & Wolf, G. (1973). How to analyse vector-meson production in inelastic lepton scattering. Nuclear Physics, Section B, 61(C), 381–413. https://doi.org/10.1016/0550-3213(73)90371-4