CLAS physics database search results Measurement E151M903 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 126 -0.1644 0.7904 0.0336 0.85 246 0.3008 0.8153 0.0409 0.75 222 1.516 0.8445 0.1039 0.85 90 1.2056 0.7763 0.0846 0.85 234 1.3316 0.8609 0.0924 0.85 246 1.7156 0.8826 0.1165