CLAS physics database search results Measurement E151M2674 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.65 282 -0.2196 0.2409 0.0303 0.75 282 -0.2609 0.271 0.0305 0.85 102 0.1836 0.2723 0.0302 0.95 102 0.2482 0.2623 0.0304 0.65 294 -0.3858 0.3338 0.031 0.75 282 -0.1314 0.3711 0.0301 0.85 102 -0.2536 0.3049 0.0304