CLAS physics database search results Measurement E151M383 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Data errors Systematic errors degrees 0.65 126 -1.5075 0.5814 0.0956 0.65 246 -0.0138 0.8484 0.03 0.75 234 3.6296 3.6296 0.2206 0.75 258 1.8727 1.2585 0.1167 0.85 258 1.8648 1.1974 0.1162 0.55 246 0.277 0.7061 0.0346 0.85 270 0.3837 0.6519 0.0383 0.95 102 -0.1676 0.6202 0.0317