CLAS physics database search results Measurement E151M2878 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.75 138 0.0564 0.2787 0.03 0.75 234 -0.1604 0.2739 0.0302 0.75 246 0.1586 0.2528 0.0302 0.95 114 0.1256 0.282 0.0301 0.65 234 -0.1345 0.3756 0.0301 0.65 246 -0.4845 0.2864 0.0315 0.75 234 -0.096 0.375 0.0301 0.75 246 0.3268 0.3283 0.0307 0.75 258 -0.178 0.3642 0.0302 0.85 234 -0.1042 0.4102 0.0301 0.85 246 -0.4199 0.2614 0.0312