CLAS physics database search results Measurement E151M1687 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.75 222 -0.9471 1.2375 0.0627 0.55 150 -0.9606 0.9339 0.0649 0.65 222 0.7548 0.979 0.0543 0.75 210 1.0587 0.8582 0.0702 0.75 222 0.0214 0.9193 0.03