CLAS physics database search results Measurement E151M3346 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.85 222 -0.1054 0.2456 0.0301 0.85 234 0.4533 0.2336 0.0313 0.65 294 0.0082 0.2474 0.03 0.75 210 -0.1633 0.257 0.0302 0.85 102 0.2289 0.231 0.0303 0.85 234 -0.6058 0.23 0.0324