CLAS physics database search results Measurement E151M434 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Data errors Systematic errors degrees 0.75 138 -0.1737 0.7775 0.0319 0.75 234 0.2832 0.7388 0.0347 0.75 246 1.4274 0.6151 0.0933 0.95 114 0.5773 0.674 0.0467 0.65 234 0.1611 1.0678 0.0315 0.65 246 0.682 1.2659 0.0509 0.75 234 -0.3338 0.888 0.0361 0.75 246 -0.1874 0.8875 0.0321 0.75 258 -0.7717 0.7498 0.0553 0.85 234 0.7894 1.2239 0.0562 0.85 246 2.329 1.1159 0.1434