CLAS physics database search results Measurement E151M868 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.85 210 0.3461 0.8829 0.0376 0.85 222 -0.1457 0.8353 0.0315 0.85 246 0.1769 0.7692 0.0322 0.85 258 -0.3574 0.7361 0.0381 0.95 258 -0.0239 1.2599 0.03 0.95 282 0.0824 1.0649 0.0305 0.75 114 -0.31 0.9759 0.0415 0.85 246 -0.9338 0.8822 0.0913 0.85 258 -0.8141 0.8584 0.0809 0.95 234 0.8276 2.8276 0.0821 0.95 270 -0.0894 2.3204 0.0311