CLAS physics database search results Measurement E151M473 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.55 78 -0.8793 0.4071 0.0616 0.55 90 -1.9885 1.9885 0.1253 0.65 90 -0.3379 0.4576 0.0364 0.65 258 0.3404 0.4672 0.0365 0.65 270 0.3653 0.4403 0.0374 0.75 126 1.2201 0.5237 0.0804 0.75 246 -0.3469 0.4429 0.0367 0.75 258 -0.4694 0.3196 0.0415 0.75 270 -0.1979 0.4181 0.0324 0.85 126 -0.7365 0.423 0.0541 0.85 138 0.1551 0.5034 0.0315 0.85 150 0.5781 0.4595 0.0464 0.85 174 -0.2825 0.4407 0.0346 0.85 246 0.138 0.5148 0.0312 0.95 150 -0.0684 0.4996 0.0303 0.95 162 0.0726 0.4725 0.0303