CLAS physics database search results Measurement E151M2715 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.65 234 -0.322 0.4403 0.0307 0.65 246 0.6305 0.2248 0.0325 0.65 258 -0.0865 0.2984 0.03 0.75 246 -0.0605 0.3694 0.03 0.85 246 0.3417 0.3038 0.0308 0.55 246 -0.5787 0.2344 0.0322 0.65 234 0.0987 0.2411 0.0301 0.65 258 -0.2485 0.2592 0.0304 0.75 234 -0.1128 0.2481 0.0301 0.75 246 0.0697 0.22 0.03