CLAS physics database search results Measurement E151M2090 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.85 210 -0.193 1.0071 0.0325 0.85 222 -1.4988 0.8977 0.102 0.85 246 0.3445 0.8864 0.0374 0.85 258 -1.3493 0.829 0.0928 0.95 258 0.3182 1.4818 0.0364 0.95 282 -0.5623 1.2175 0.0473 0.75 114 -2.4477 1.0432 0.2269 0.85 246 -1.0143 1.0721 0.0979 0.85 258 0.4621 1.074 0.052 0.95 234 -1.4769 3.1845 0.139 0.95 270 3.8482 2.6219 0.3549