CLAS physics database search results Measurement E151M1205 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 114 -0.3912 0.9107 0.0414 0.75 270 0.3717 0.8414 0.0405 0.85 102 -0.3505 0.8357 0.0395 0.85 114 0.0715 0.8141 0.0305 0.85 126 -1.1443 0.7728 0.0889 0.85 186 2.0781 1.0395 0.1548 0.85 198 -0.0496 0.7758 0.0302 0.85 210 -0.9388 0.7406 0.0749