Abstract |
A sample of e^+ pi^+ pi^- events with Q^2 > 2.5 GeV^2, 40 < W < 120 GeV and t' = |t| - t_min in the range 0.5 < t' < 3.0 GeV^2 is used to measure the r^04_00 density matrix element and the combinations r_00^5 + 2r_11^5 and r_00^1 + 2r_11^1. The t' dependences are determined. |