CLAS physics database search results Measurement E151M3444 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.75 102 0.0993 0.2707 0.0301 0.75 258 -0.0466 0.278 0.03 0.75 318 -0.1751 0.2671 0.0302 0.85 234 0.0876 0.2479 0.0301 0.85 258 -0.8029 0.2125 0.034 0.85 270 0.6383 0.2184 0.0326