CLAS physics database search results Measurement E151M2733 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.85 282 -0.0747 0.4288 0.03 0.65 270 -0.3745 0.273 0.0309 0.85 102 0.2868 0.262 0.0305 0.85 270 0.1568 0.2782 0.0302 0.85 294 0.4135 0.2743 0.0311