CLAS physics database search results Measurement E151M1189 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 222 -0.6306 0.8012 0.055 0.85 90 -0.0422 0.8361 0.0302 0.85 102 -0.6096 0.8047 0.0537 0.85 114 1.317 1.0482 0.1008 0.85 174 0.9341 0.9431 0.0746 0.85 186 -0.2257 0.7167 0.0342 0.85 198 -0.0177 0.7829 0.03 0.85 210 2.2807 0.9807 0.1694 0.85 222 -0.3684 0.8662 0.0403 0.85 234 -0.5335 0.7946 0.0492