CLAS physics database search results Measurement E151M2643 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.65 258 -0.4915 0.2879 0.0316 0.65 270 -0.1851 0.3785 0.0302 0.85 162 0.0666 0.3642 0.03 0.85 198 -0.3323 0.3412 0.0307 0.55 270 0.0926 0.2815 0.0301 0.75 174 -0.18 0.2465 0.0302 0.75 258 -0.0408 0.2817 0.03 0.85 186 0.1098 0.2592 0.0301