CLAS physics database search results Measurement E151M1677 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.75 222 -1.1995 0.9569 0.0779 0.75 234 -2.1277 0.6078 0.1273 0.85 222 -1.6242 0.9319 0.0991 0.85 234 0.8129 1.1459 0.056