CLAS physics database search results Measurement E151M737 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 282 -2.3188 1.7259 0.2161 0.85 90 -0.4377 2.6441 0.0503 0.55 282 0.0308 0.3958 0.0301 0.65 270 0.2683 0.4383 0.0348 0.65 294 0.5992 0.4681 0.0495 0.75 282 -0.1227 0.3668 0.0311 0.75 294 0.4619 0.4406 0.0426 0.85 90 -0.6031 0.4396 0.0497 0.85 102 -0.1249 0.4686 0.0311 0.85 282 -0.2386 0.4312 0.0338 0.95 102 0.0311 0.7158 0.0301 0.95 114 0.5165 0.7589 0.0453 0.95 126 -1.0668 0.622 0.0762