CLAS physics database search results Measurement E151M3526 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.55 90 -0.1831 0.2722 0.0302 0.65 102 0.3147 0.247 0.0307 0.75 54 -0.3964 0.2573 0.031 0.75 102 -0.0138 0.2857 0.03 0.75 270 -0.4541 0.2229 0.0313 0.85 102 -0.0386 0.2745 0.03 0.85 210 -0.3829 0.2671 0.031 0.85 234 0.0164 0.2495 0.03 0.85 270 -0.2791 0.2469 0.0305 0.95 294 -0.728 0.1862 0.0333 0.95 306 -0.2891 0.2035 0.0306 0.95 318 0.0205 0.2794 0.03