CLAS physics database search results Measurement E151M2915 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.75 270 -0.0061 0.2693 0.03 0.95 102 -0.194 0.2653 0.0302 0.95 114 -0.503 0.2745 0.0316