CLAS physics database search results Measurement E151M2400 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.85 78 -0.3299 1.067 0.0384 0.85 90 -0.4314 0.9379 0.0433 0.85 102 1.7115 0.8605 0.1277 0.85 114 0.7502 1.0061 0.0621 0.85 186 -0.5439 0.9958 0.0495 0.85 198 -0.8468 0.9627 0.0683 0.85 210 -1.1746 0.7906 0.0903 0.85 222 0.6184 0.8925 0.054 0.85 234 -1.8773 0.9182 0.1394 0.95 186 0.6912 1.0654 0.0584 0.95 210 -0.586 0.8733 0.052 0.95 222 -2.1746 0.8119 0.1605 0.95 234 -1.0018 0.9776 0.0786