CLAS physics database search results Measurement E151M325 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Data errors Systematic errors degrees 0.75 234 -0.6433 0.7817 0.049 0.75 246 -0.0385 0.8278 0.0301 0.85 282 3.3595 3.3595 0.2045 0.95 282 0.0665 0.7933 0.0303 0.65 246 -0.6341 0.5795 0.0494 0.75 258 -0.3939 0.6758 0.0387 0.75 270 1.3498 0.5794 0.0888 0.85 138 -2.0682 0.4546 0.1315 0.85 246 0.226 0.6329 0.0331 0.85 258 0.1529 0.5717 0.0315 0.85 270 -0.261 0.565 0.0341 0.95 258 -0.2318 0.5653 0.0333