CLAS physics database search results Measurement E151M813 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 90 0.7535 0.6028 0.0578 0.75 102 -0.6638 0.4802 0.0546 0.85 102 -0.1303 0.6584 0.0312 0.85 234 0.37 0.7944 0.0386 0.85 258 -0.6223 0.6985 0.0507 0.85 270 -0.7255 0.6207 0.0563 0.85 282 0.1192 0.7224 0.031 0.95 306 -0.1837 0.8813 0.0323 0.75 114 0.0707 1.1731 0.0307 0.75 126 0.5241 1.216 0.0569 0.75 258 -0.0281 0.9573 0.0301 0.85 270 -0.9539 0.9151 0.093