CLAS physics database search results Measurement E151M2123 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.65 126 -1.6112 0.814 0.109 0.75 210 -0.7892 0.9904 0.0595 0.75 234 -2.6173 2.6173 0.1729 0.85 90 1.1062 0.8126 0.078 0.85 102 -0.554 0.9611 0.0469 0.85 222 0.2924 0.8522 0.0355 0.85 234 0.0602 1.041 0.0303 0.65 234 0.1271 0.8426 0.0322 0.65 294 0.1982 0.7469 0.0351 0.75 126 -0.4352 0.9852 0.05 0.75 294 -0.4128 0.7699 0.0484 0.85 102 1.3519 1.1153 0.1278 0.85 222 -0.1676 0.7857 0.0337