CLAS physics database search results Measurement E151M3375 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.75 270 -0.1003 0.2566 0.0301 0.85 102 -0.1268 0.2648 0.0301 0.85 114 0.272 0.2266 0.0305 0.65 138 0.01 0.249 0.03 0.65 210 0.3222 0.2311 0.0307 0.85 102 -0.4166 0.2285 0.0311