CLAS physics database search results Measurement E151M3624 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.75 222 -0.1714 0.2795 0.0302 0.85 90 -0.1975 0.2632 0.0303 0.85 210 0.0755 0.2683 0.03 0.95 210 -0.034 0.2501 0.03 0.95 222 -0.1011 0.2691 0.0301 0.95 234 -0.3649 0.2516 0.0309