CLAS physics database search results Measurement E151M2152 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.65 282 -0.4392 0.6304 0.0414 0.75 222 -0.272 0.851 0.0348 0.85 114 -0.9025 0.7895 0.0659 0.85 210 -1.7919 0.7965 0.1204 0.85 222 0.5146 0.8588 0.045 0.65 294 -1.2517 0.7562 0.1189 0.75 270 0.8225 0.7397 0.0813 0.75 282 -0.7172 0.7835 0.0724 0.85 210 -3.2557 3.2557 0.3007