CLAS physics database search results Measurement E151M711 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.55 210 1.6191 0.7605 0.1035 0.65 210 0.4487 0.7343 0.0407 0.75 198 1.0451 0.7948 0.0706 0.75 210 0.0113 0.6685 0.03 0.75 258 -0.2038 0.6967 0.0325 0.75 270 -0.2443 0.6481 0.0335 0.75 282 0.8314 0.7182 0.059 0.85 126 0.5604 0.6755 0.0456 0.85 210 -0.2208 0.613 0.0329