CLAS physics database search results Measurement E151M442 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.45 42 -0.5573 0.6022 0.0455 0.65 222 1.2181 0.671 0.0812 0.85 234 0.1137 0.6679 0.0308 0.45 222 -0.6798 0.8618 0.0508 0.55 222 0.7624 1.2674 0.0548 0.55 234 1.3149 1.6323 0.0847 0.75 234 -0.2162 0.8775 0.0327 0.85 138 -0.6222 0.9021 0.048 0.85 222 2.0843 1.2543 0.129 0.85 234 -0.1926 0.984 0.0322