CLAS physics database search results Measurement E151M706 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 210 0.2763 0.6416 0.0344 0.75 294 0.3543 0.6204 0.037 0.85 222 2.2356 2.2356 0.14 0.85 234 -0.2218 0.4941 0.0329 0.85 246 0.8488 0.5835 0.06