CLAS physics database search results Measurement E151M200 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Data errors Systematic errors degrees 0.55 270 0.1415 0.3601 0.0312 0.65 258 -0.4927 0.2678 0.0429 0.65 270 -0.0177 0.2561 0.0346 0.75 150 1.2635 0.9858 0.0818 0.75 162 0.4411 0.4859 0.0406 0.75 186 -0.6567 0.4679 0.0496 0.75 246 -0.0592 0.3084 0.0375 0.75 258 -0.5303 0.305 0.0558 0.75 270 0.1273 0.3595 0.031 0.85 150 0.6096 0.4165 0.0489 0.85 162 0.033 0.3518 0.0316 0.85 174 -0.221 0.2968 0.0334 0.85 186 0.9674 0.3781 0.0668