CLAS physics database search results Measurement E151M2865 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.65 222 -0.0122 0.2815 0.03 0.75 210 0.1206 0.2901 0.0301 0.75 234 -0.2143 0.2788 0.0303 0.55 42 -0.6541 0.2848 0.0327 0.65 210 -0.2586 0.3457 0.0304 0.75 234 0.3909 0.3902 0.031 0.85 222 0.1279 0.42 0.0301