CLAS physics database search results Measurement E151M2024 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.75 150 0.4189 0.9645 0.0405 0.75 234 -0.9712 0.8182 0.0699 0.85 222 -0.0658 1.0225 0.0303 0.85 246 1.4732 0.8984 0.1004 0.65 234 2.0011 1.1723 0.1863