CLAS physics database search results Measurement E151M1656 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.75 138 -0.2994 1.015 0.035 0.75 234 1.7688 0.8992 0.1102 0.75 246 -0.0768 0.9255 0.0304 0.95 114 0.8303 0.8865 0.0581 0.65 234 -1.2094 1.1269 0.0765 0.65 246 -1.8273 0.8531 0.1104 0.75 234 0.2666 1.1646 0.0338 0.75 246 1.147 0.9992 0.0731 0.75 258 -0.3605 1.1051 0.0366 0.85 234 0.459 1.2614 0.0402 0.85 246 -0.0494 1.0411 0.0301