CLAS physics database search results Measurement E151M2861 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.85 234 -0.4015 0.2704 0.0311 0.65 246 -0.5026 0.2909 0.0316 0.75 246 -0.0324 0.4008 0.03