CLAS physics database search results Measurement E151M1403 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.35 42 0.3393 0.9454 0.0486 0.35 54 -0.9323 0.8755 0.1093 0.45 54 -0.8027 0.8009 0.0954 0.45 222 1.5957 0.7461 0.1825 0.55 210 -0.2657 0.8728 0.0424 0.55 234 1.1562 0.7402 0.1338 0.75 222 0.7592 0.8032 0.0907 0.75 234 -0.5538 0.7237 0.0693 0.85 222 0.5136 0.7151 0.0652 0.85 234 0.6837 0.7495 0.0827