CLAS physics database search results Measurement E151M3645 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.85 90 -0.1904 0.2499 0.0302 0.85 198 -0.0727 0.2815 0.03 0.85 210 -0.5802 0.1973 0.0322