CLAS physics database search results Measurement E151M2145 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.65 138 -0.5935 2.1526 0.0622 0.75 222 -2.7255 1.9862 0.2523 0.75 282 -3.0967 1.5785 0.2862 0.85 114 -4.1848 2.4242 0.3858 0.85 210 2.7964 2.0738 0.2587 0.65 282 0.4746 0.6592 0.043 0.75 270 -1.4804 0.6201 0.1009 0.75 282 0.1879 0.6581 0.0324 0.85 114 -0.1969 0.8233 0.0326 0.85 234 -0.7142 0.8673 0.0553