CLAS physics database search results Measurement E151M2398 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.65 270 -0.2679 1.0419 0.0357 0.75 186 -0.0752 1.0052 0.0305 0.75 198 1.8602 0.9567 0.1382 0.75 210 1.6794 0.9197 0.1254 0.75 222 0.6309 1.0386 0.0547 0.75 270 -0.622 0.9943 0.0542 0.75 282 -0.6247 0.9625 0.0543 0.85 90 0.6046 0.7345 0.0531 0.85 102 0.6563 0.8107 0.0563 0.85 114 -1.9462 0.7907 0.1443 0.85 126 -0.0762 1.0812 0.0305 0.85 174 -2.062 0.8727 0.1525 0.85 186 0.0328 0.9906 0.0301 0.85 198 -1.2999 0.7745 0.0989 0.85 210 0.3331 0.9039 0.0385 0.85 222 -0.7085 0.9601 0.0595 0.85 234 -0.0987 0.8858 0.0308 0.95 198 -0.3851 1.0769 0.041 0.95 222 0.4197 0.9605 0.0427