CLAS physics database search results Measurement E151M816 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 234 -0.6905 0.847 0.0704 0.85 246 -1.8539 0.9166 0.1737 0.65 234 1.1497 0.8124 0.0812 0.65 246 -0.2208 0.7537 0.0333 0.75 114 -0.0765 0.7884 0.0304 0.75 126 -1.3886 0.5976 0.0959 0.75 138 0.0812 0.8075 0.0305 0.75 222 0.1271 0.8572 0.0311 0.75 234 -0.4125 0.6732 0.0404 0.75 246 0.2997 0.8399 0.0359 0.85 234 0.6094 0.8742 0.05