CLAS physics database search results Measurement E151M84 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Data errors Systematic errors degrees 0.55 42 2.1787 0.8206 0.2497 0.55 222 -0.3476 0.7273 0.0496 0.55 234 0.2898 0.6692 0.0446 0.55 246 -0.6447 0.6207 0.0793 0.65 54 -0.4654 0.6301 0.0609 0.65 222 -0.7001 0.5604 0.0851 0.65 234 0.8801 0.6394 0.1045 0.65 246 0.9276 0.6619 0.1097 0.65 258 -0.4399 0.6208 0.0584 0.75 222 0.7451 0.7845 0.0899 0.75 234 0.3703 0.5217 0.0517 0.75 246 -0.6911 0.4988 0.0842 0.75 258 1.5076 0.6194 0.1741 0.85 222 -0.7392 0.6205 0.0893 0.85 234 0.9095 0.6264 0.1077 0.85 246 0.675 0.5591 0.0824