CLAS physics database search results Measurement E151M1900 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.45 270 -0.565 0.8397 0.0455 0.55 126 -0.389 0.9362 0.0382 0.55 270 -0.154 0.9594 0.0314 0.65 114 -2.1053 0.7278 0.1311 0.65 222 -2.3825 2.3825 0.1475 0.65 294 0.1268 0.8102 0.031 0.75 126 0.8732 0.8987 0.0608 0.75 210 0.054 0.8661 0.0302 0.75 222 1.5146 0.7517 0.0966 0.75 234 -0.2521 0.7629 0.0337 0.85 90 0.7825 0.8238 0.0561 0.85 114 -0.0415 0.8836 0.0301 0.85 210 -1.6608 0.7258 0.105 0.85 222 0.7809 0.9041 0.056 0.85 234 0.3618 0.8916 0.0372 0.85 258 1.2646 0.8389 0.0823