CLAS physics database search results Measurement E151M730 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 270 2.0064 2.141 0.1876 0.85 150 -0.2529 3.0218 0.038 0.65 270 -0.7673 0.3222 0.0586 0.85 138 0.6547 0.599 0.0524 0.95 162 -0.2978 0.8619 0.0358