CLAS physics database search results Measurement E151M1960 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.65 282 -3.2293 2.1548 0.2983 0.65 294 -4.6127 2.1067 0.425 0.75 282 -0.7724 2.1661 0.0771 0.85 78 2.5915 3.2569 0.24 0.85 90 -0.0005 2.9041 0.03 0.85 114 5.1644 2.8653 0.4756 0.55 270 -0.4018 0.5256 0.0398 0.55 282 -1.0439 0.4218 0.0742 0.75 282 -0.596 0.4322 0.049 0.85 90 -0.716 0.4884 0.0554 0.85 102 0.123 0.6031 0.031 0.85 282 0.3968 0.5136 0.0396