CLAS physics database search results Measurement E151M2420 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.65 282 -2.2669 0.8192 0.1671 0.75 102 -0.2318 1.1055 0.0344 0.75 114 -1.2355 1.0739 0.0945 0.75 198 -1.7655 0.9234 0.1315 0.75 282 0.0037 1.0403 0.03 0.85 102 -0.9815 0.854 0.0772 0.85 114 0.4698 1.0191 0.0454 0.85 126 2.7641 0.9377 0.2027 0.85 174 0.7011 1.12 0.059 0.85 198 0.6036 0.8371 0.0531 0.85 210 -1.2877 0.9562 0.0981 0.85 222 -0.3027 0.9211 0.0372