CLAS physics database search results Measurement E151M270 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Data errors Systematic errors degrees 0.75 138 -0.5476 0.7934 0.0446 0.75 246 1.6592 1.1435 0.1043 0.85 102 -1.0472 0.5662 0.0698 0.85 114 0.3722 1.1565 0.0374 0.85 282 1.567 1.0891 0.099 0.65 294 0.0843 0.6298 0.0305 0.85 102 -0.5961 0.55 0.0476 0.85 126 0.0304 0.5717 0.0301 0.85 162 -0.0731 0.5876 0.0303 0.85 270 -0.0893 0.5563 0.0305 0.85 294 0.8538 0.5629 0.0608