  We provide a framework to analyze the electroproduction process ep -> ep rho
with a polarized target, writing the angular distribution of the rho decay
products in terms of spin density matrix elements that parameterize the
hadronic subprocess gamma* p -> rho p. Using the helicity basis for both photon
and meson, we find a representation in which the expressions for a polarized
and unpolarized target are related by simple substitution rules.

High Energy Physics - Phenomenology