CLAS physics database search results Measurement E151M1915 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.65 282 0.1754 0.8311 0.0318 0.65 294 0.0152 0.8268 0.03 0.75 138 -0.9567 0.8499 0.0653 0.75 222 -2.5258 2.5258 0.156 0.75 246 -0.1398 0.7535 0.0312 0.85 102 0.0044 0.7512 0.03 0.85 114 0.6964 0.7957 0.0518 0.85 210 -0.8132 0.8281 0.0577 0.85 222 1.0283 0.6824 0.0692 0.85 234 -0.7456 0.7279 0.0542 0.85 246 0.0046 0.8012 0.03