CLAS physics database search results Measurement E151M461 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Data errors Systematic errors degrees 0.55 222 0.6258 0.7477 0.049 0.65 222 0.5383 0.6984 0.0448 0.55 234 0.8463 1.2512 0.0591 0.75 222 -1.4409 0.5684 0.0918 0.75 234 0.7167 1.2342 0.0526 0.85 222 0.7427 1.2135 0.0539