CLAS physics database search results Measurement E151M693 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.65 282 -0.5437 0.6424 0.0448 0.65 294 -0.1493 0.6879 0.0314 0.75 138 -1.149 0.5914 0.0764 0.75 222 -0.3742 0.6811 0.0377 0.75 246 0.033 0.6439 0.0301 0.85 102 0.4648 0.6689 0.0413 0.85 114 -0.7645 0.6138 0.0556 0.85 210 -0.3364 0.6674 0.0364 0.85 222 0.4557 0.6835 0.0409 0.85 234 -0.0149 0.668 0.03 0.85 246 1.51 0.7059 0.0971