CLAS physics database search results Measurement E151M104 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Data errors Systematic errors degrees 0.45 54 2.1475 1.0372 0.2462 0.55 54 0.3854 0.8137 0.0531 0.55 234 0.2874 0.8462 0.0444 0.55 246 -0.0211 0.6821 0.0301 0.65 54 1.0098 0.8149 0.1187 0.65 222 -0.0882 0.7284 0.0316 0.65 234 -0.2407 0.6177 0.0406 0.65 246 1.1587 0.693 0.1352 0.65 258 -0.8693 0.6825 0.1033 0.75 222 0.9819 0.815 0.1157 0.75 234 -1.2651 0.6368 0.147 0.75 246 -0.3041 0.5357 0.0458 0.85 234 0.1846 0.6361 0.0366 0.85 246 -0.1953 0.5888 0.0373