CLAS physics database search results Measurement E151M945 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.35 282 -0.0012 0.6564 0.03 0.45 282 1.2723 0.6575 0.0977 0.45 294 -0.1836 0.607 0.0329 0.55 282 0.1296 0.6131 0.0315 0.75 66 -0.4172 0.5051 0.0428 0.75 78 -0.2282 0.5573 0.0343 0.75 270 0.2027 0.6516 0.0335 0.75 282 2.2755 2.2755 0.169 0.85 66 0.6969 0.683 0.0591 0.85 90 -0.8655 0.5156 0.07