CLAS physics database search results Measurement E151M1206 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 270 1.7141 1.0203 0.1288 0.85 102 0.0988 0.7565 0.0309 0.85 114 0.9562 0.925 0.0761 0.85 186 -1.3615 0.6808 0.1039 0.85 198 -0.6845 0.7601 0.0583 0.85 210 -1.0458 0.723 0.0821 0.85 222 -1.2186 0.6542 0.094