CLAS physics database search results Measurement E151M10 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Data errors Systematic errors degrees 0.45 282 0.4874 0.4675 0.063 0.55 270 -0.0698 0.4306 0.031 0.55 282 0.7213 0.3624 0.0874 0.65 258 -0.4745 0.3702 0.0618 0.65 270 0.1724 0.3538 0.0358 0.65 282 -0.3482 0.4087 0.0497 0.75 258 -0.8771 0.2803 0.1042 0.75 270 -0.2905 0.3227 0.0446 0.85 138 -0.2 0.461 0.0377 0.85 150 0.6265 0.474 0.0773 0.85 162 -0.1579 0.3439 0.035 0.85 174 -0.0974 0.3167 0.032 0.85 186 0.4936 0.3479 0.0637 0.85 198 -0.0993 0.303 0.0321 0.85 210 -0.3708 0.3223 0.0518 0.85 222 0.5779 0.493 0.0723 0.95 186 0.4761 0.3793 0.0619 0.95 210 -0.2801 0.3488 0.0438