CLAS physics database search results Measurement E151M2676 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.55 270 -0.2056 0.2604 0.0303 0.75 294 0.5189 0.2641 0.0317 0.85 90 0.0854 0.277 0.03 0.85 126 -0.1759 0.2761 0.0302 0.45 282 0.0261 0.3967 0.03 0.55 270 0.3693 0.3275 0.0309 0.65 258 0.4642 0.2803 0.0314 0.65 270 -0.0259 0.3695 0.03 0.65 282 -0.5592 0.2562 0.032 0.85 102 0.0254 0.3815 0.03 0.85 114 -0.1362 0.3787 0.0301