CLAS physics database search results Measurement E151M3614 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.85 198 0.1921 0.2725 0.0302 0.85 234 -0.0332 0.2566 0.03 0.95 198 -0.3987 0.2457 0.031 0.95 210 -0.1294 0.2563 0.0301 0.95 222 0.0614 0.262 0.03 0.95 234 0.0751 0.262 0.03