CLAS physics database search results Measurement E151M703 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.65 126 -0.2129 0.5774 0.0327 0.75 222 -0.3719 0.5834 0.0376 0.75 234 1.2298 0.5285 0.081 0.75 282 -0.5268 0.4423 0.044 0.85 102 -0.2738 0.6172 0.0344 0.85 114 -0.4232 0.5475 0.0396 0.85 198 -0.0601 0.6049 0.0302 0.85 210 0.5827 0.5408 0.0466 0.85 222 1.0632 0.6069 0.0716