CLAS physics database search results Measurement E151M928 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 210 0.7196 0.7416 0.0559 0.75 270 1.3989 0.6038 0.0966 0.75 282 -0.2841 0.5418 0.0353 0.85 114 0.0962 0.6395 0.0307 0.85 210 0.1424 0.712 0.0314 0.45 270 -0.2531 0.6376 0.038 0.85 114 -0.0764 0.9881 0.0308 0.85 126 -1.4784 0.7663 0.1397 0.85 210 0.9268 0.9973 0.0906