CLAS physics database search results Measurement E151M448 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.65 222 -0.6681 0.7821 0.0502 0.75 246 -0.8661 0.7213 0.0602 0.85 234 0.3165 1.0057 0.0355 0.85 258 0.7248 1.1936 0.053 0.55 234 -0.4473 0.7139 0.0408 0.85 126 0.9459 0.7477 0.0658 0.85 234 0.0915 0.6605 0.0305