CLAS physics database search results Measurement E151M1082 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.55 90 -0.8974 0.7431 0.0721 0.65 102 -0.5075 0.7581 0.0477 0.75 54 -0.0842 0.8159 0.0306 0.75 102 0.4108 0.9739 0.0424 0.75 270 1.4363 0.9919 0.1092 0.85 102 -0.1537 0.8515 0.032 0.85 210 0.4842 0.9629 0.0464 0.85 234 0.3596 0.818 0.0399 0.85 270 -0.3247 0.7304 0.0383 0.95 294 -0.536 0.6434 0.0493 0.95 306 1.1149 0.6582 0.0868 0.95 318 -0.6 0.6577 0.0531