CLAS physics database search results Measurement E151M433 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Data errors Systematic errors degrees 0.55 162 -0.9712 0.7258 0.0672 0.65 234 1.4002 0.6977 0.0917 0.75 138 0.6259 0.7653 0.049 0.75 150 -1.2214 0.6382 0.0814 0.75 234 1.7113 0.662 0.1101 0.85 234 0.8777 0.6762 0.0621 0.55 234 -0.0331 1.0608 0.0301 0.65 234 0.8706 1.2593 0.0604 0.85 234 -1.1579 0.5228 0.0759 0.85 258 -1.2628 0.5196 0.0817