CLAS physics database search results Measurement E151M465 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Data errors Systematic errors degrees 0.75 222 0.9914 1.1892 0.0668 0.55 150 0.0241 0.7364 0.03 0.65 222 1.5045 0.656 0.0979 0.75 210 -0.1072 0.671 0.0307 0.75 222 0.3289 0.6899 0.0363