CLAS physics database search results Measurement E151M1655 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.55 162 -1.8254 0.8927 0.1134 0.65 234 -1.1268 1.0103 0.0739 0.75 138 0.7119 1.0192 0.0522 0.75 150 -0.9321 0.8475 0.0634 0.75 234 0.3959 1.0292 0.0382 0.85 234 -1.4609 0.8899 0.0926 0.55 234 1.108 1.1933 0.0711 0.65 234 -1.8514 0.8686 0.1118 0.85 234 -2.1971 0.6281 0.1312 0.85 258 -0.7831 0.9266 0.0545