CLAS physics database search results Measurement E151M1935 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.35 78 0.0777 0.8373 0.0304 0.35 282 -0.6684 0.8613 0.0504 0.65 198 -0.9811 0.799 0.0666 0.65 282 -1.3084 0.7694 0.0848 0.75 66 -1.4944 0.7018 0.0954 0.75 210 0.2443 0.7198 0.0335 0.75 270 -0.1247 0.6644 0.0309 0.75 282 -1.5718 0.6984 0.0999 0.85 114 -0.0017 0.7051 0.03 0.85 126 0.4203 0.8561 0.0394 0.85 198 0.2191 0.7798 0.0328 0.85 222 -1.044 0.68 0.07