CLAS physics database search results Measurement E151M3112 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.65 222 -0.1955 0.2694 0.0303 0.75 198 0.0212 0.2772 0.03 0.75 210 -0.367 0.2418 0.0309 0.85 126 0.0505 0.2728 0.03 0.85 138 -0.2666 0.2596 0.0305 0.85 222 0.2438 0.2212 0.0304