CLAS physics database search results Measurement E151M2862 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.65 222 0.1413 0.2866 0.0301 0.85 234 0.0034 0.2751 0.03 0.65 246 0.0369 0.3844 0.03 0.65 258 -0.168 0.3995 0.0302 0.75 246 0.1674 0.4063 0.0302