CLAS physics database search results Measurement E151M3644 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.65 282 0.165 0.2684 0.0302 0.85 90 -0.1647 0.2745 0.0302 0.85 102 -0.1928 0.2386 0.0302 0.85 114 -0.0163 0.2493 0.03 0.85 198 -0.1573 0.2235 0.0302 0.85 210 -0.0661 0.2773 0.03 0.85 222 -0.144 0.2604 0.0301