CLAS physics database search results Measurement E151M924 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.85 102 2.9912 2.2136 0.2777 0.85 126 -1.5068 2.0789 0.1423 0.85 210 1.0066 2.0155 0.0976 0.65 294 -0.1713 0.5492 0.032 0.85 114 0.866 0.7189 0.0643 0.85 234 0.791 0.7009 0.06