CLAS physics database search results Measurement E151M2909 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.75 222 0.311 0.3821 0.0306 0.55 150 -0.3065 0.2698 0.0306 0.65 222 0.0468 0.2872 0.03 0.75 210 -0.4239 0.2519 0.0312 0.75 222 -0.1857 0.2724 0.0302