CLAS physics database search results Measurement E151M1188 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 270 1.7076 1.0451 0.1284 0.85 102 -0.0782 0.7698 0.0305 0.85 114 -1.3065 0.6138 0.1001 0.85 126 0.2377 0.9967 0.0347 0.85 174 -0.4087 0.8286 0.0423 0.85 186 -1.7857 0.6557 0.1339 0.85 198 -0.767 0.7747 0.0636 0.85 210 0.6883 0.9309 0.0586 0.85 222 -0.3414 0.8615 0.039 0.85 234 -0.6324 0.8541 0.0551