CLAS physics database search results Measurement E151M3658 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.75 186 0.0128 0.2795 0.03 0.85 102 -0.1615 0.2657 0.0302 0.85 114 0.2799 0.259 0.0305 0.85 126 -0.6085 0.2108 0.0324 0.85 210 -0.4352 0.2505 0.0312