CLAS physics database search results Measurement E151M902 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.85 222 0.45 0.8443 0.0512 0.85 234 0.0875 0.8317 0.0311 0.65 294 -0.3946 0.6192 0.0396 0.75 210 0.5509 0.9097 0.047 0.85 102 0.3013 0.7696 0.0359 0.85 234 0.2315 0.8718 0.0336