CLAS physics database search results Measurement E151M163 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Data errors Systematic errors degrees 0.45 54 -0.2191 0.7282 0.039 0.55 42 0.4668 0.8569 0.061 0.55 54 -0.2037 0.7992 0.0379 0.55 222 0.1741 0.7778 0.0359 0.65 234 0.8532 0.7488 0.1016 0.75 234 0.0716 0.6568 0.0311 0.85 222 0.034 0.7027 0.0302 0.85 234 1.6134 0.6506 0.186 0.85 246 -1.4099 0.5266 0.1632