Model-independent amplitude analysis for the reaction πN → ρΔ

A method is proposed for determining the amplitudes for the reaction πN → ?Δ using only those moments of the joint decay angular distribution 〈Y_L1^M₁Y_L2^M₂〉 with both L₁ and L₂ even. The solution is not unique; both continuous and discrete ambiguities exist. The conditions under which an analysis is possible are studied in detail; in addition to certain positivity conditions on the joint density matrix, a complicated inequality involving the experimental moments must be satisfied. This condition defines a non-convex domain in the space of the moments. We apply our methods to the high-statistics experimental data at 3.7 GeV/c.