CLAS physics database search results Measurement E151M2354 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.85 234 0.7329 0.8582 0.061 0.85 246 -0.6773 0.7628 0.0576 0.85 258 -1.8701 0.6208 0.1389 0.95 234 -0.2946 0.7644 0.0368 0.95 306 0.255 0.7514 0.0352