CLAS physics database search results Measurement E151M880 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 126 -1.5753 0.5805 0.1076 0.75 222 0.5689 0.5884 0.0527 0.85 78 -0.4271 0.5166 0.0461 0.85 90 -1.9236 0.7256 0.1801 0.85 222 0.3025 0.9043 0.036 0.85 234 0.8812 0.6567 0.0763 0.95 246 1.1493 1.3819 0.0812 0.95 258 0.3094 1.2843 0.0362 0.95 282 -2.9529 1.5934 0.2742