CLAS physics database search results Measurement E151M1178 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.85 78 -0.3942 0.8788 0.0416 0.85 90 -0.3104 0.7895 0.0376 0.85 102 1.8943 0.8789 0.1417 0.85 114 -0.9909 0.7556 0.0784 0.85 186 -0.2411 0.8391 0.0348 0.85 198 -0.7708 0.7634 0.0638 0.85 210 -0.117 0.7122 0.0312 0.85 222 0.9981 0.856 0.0789 0.85 234 0.6463 0.9989 0.056 0.95 186 0.8724 1.0427 0.0705 0.95 210 -1.4198 0.5719 0.108 0.95 222 0.9234 0.9233 0.0739 0.95 234 0.7617 0.9229 0.0632