CLAS physics database search results Measurement E151M1924 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.45 282 -1.0768 0.6692 0.0718 0.65 126 1.0313 0.695 0.0693 0.65 198 0.4008 0.7462 0.0386 0.65 282 -1.5719 0.5839 0.0999 0.65 294 -1.1098 0.6207 0.0736 0.75 198 0.1018 0.635 0.0306 0.75 210 -0.7152 0.6196 0.0527 0.75 222 -0.8624 0.553 0.0603 0.75 282 -0.291 0.566 0.0348 0.85 114 1.3812 0.5383 0.0889 0.85 234 -0.3205 0.7224 0.0357