CLAS physics database search results Measurement E151M1204 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 114 -0.5688 0.8093 0.0513 0.75 210 -2.5879 0.441 0.1915 0.75 282 0.0941 0.7621 0.0308 0.85 126 0.9677 0.9972 0.0768 0.85 186 -1.4052 0.6474 0.107 0.85 198 -0.6363 0.7037 0.0553 0.85 270 -0.2245 0.7897 0.0342