CLAS physics database search results Measurement E151M1303 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.55 234 1.4073 0.6449 0.1615 0.55 246 -0.2247 0.7075 0.0393 0.65 234 -0.8368 0.643 0.099 0.65 246 0.9972 0.7939 0.1164 0.65 258 -1.4138 0.6122 0.1623 0.75 222 -1.1009 0.7703 0.1277 0.75 234 0.752 0.7265 0.09 0.75 246 -0.3193 0.6703 0.0469 0.75 258 0.2297 0.87 0.0396 0.85 222 -0.8349 0.7012 0.0988 0.85 234 0.3101 0.7921 0.0461 0.85 246 1.6808 0.6821 0.1919