CLAS physics database search results Measurement E151M1783 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.45 78 0.0513 0.895 0.0302 0.65 78 -0.56 0.8422 0.0453 0.65 222 -0.4239 0.8597 0.0395 0.65 234 0.9225 0.7057 0.0634 0.65 246 -0.7355 0.7444 0.0537 0.75 114 0.9923 0.8477 0.0672 0.75 126 -0.5951 0.7393 0.0469 0.75 234 -0.1274 0.8463 0.031 0.85 138 1.8594 0.6773 0.1166 0.85 234 0.8143 0.6814 0.0577 0.85 246 0.0628 0.7062 0.0302