CLAS physics database search results Measurement E151M591 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.65 90 0.3479 0.727 0.0368 0.65 102 -0.0463 0.6986 0.0301 0.75 90 -0.3641 0.707 0.0374 0.75 102 -0.2724 0.6986 0.0343 0.75 246 -0.4678 0.6675 0.0415 0.75 258 1.3207 0.7014 0.0862 0.75 270 -0.5067 0.6241 0.0431 0.85 246 0.0215 0.641 0.03 0.85 270 0.8221 0.7882 0.0585 0.85 282 0.1503 0.6202 0.0314 0.85 294 1.254 0.6887 0.0824 0.95 282 -0.1315 0.5772 0.0311 0.95 294 -0.2067 0.6217 0.0326