CLAS physics database search results Measurement E151M2892 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.65 222 -0.0709 0.3578 0.03 0.75 246 -0.2652 0.3727 0.0305 0.85 234 -0.6809 0.2038 0.0329 0.85 258 0.0967 0.4193 0.0301 0.55 234 0.3625 0.2574 0.0309 0.85 126 1.0041 1.0041 0.0361 0.85 234 -0.2714 0.2524 0.0305