CLAS physics database search results Measurement E151M1547 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.75 234 2.0479 0.5893 0.1228 0.75 246 0.851 0.9326 0.0579 0.85 282 0.699 1.0549 0.0505 0.95 282 -0.8601 0.8805 0.0583 0.65 246 1.1314 0.7296 0.0741 0.75 258 -0.4211 0.8767 0.0392 0.75 270 0.0341 0.8617 0.0301 0.85 138 1.3089 0.7222 0.084 0.85 246 1.4334 0.7869 0.091 0.85 258 -0.2261 0.7526 0.0329 0.85 270 1.2828 0.6949 0.0825 0.95 258 0.9845 0.6993 0.0662