CLAS physics database search results Measurement E151M423 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Data errors Systematic errors degrees 0.55 30 -1.0357 0.7329 0.0692 0.55 222 -0.1313 0.9035 0.031 0.55 234 0.1046 1.0396 0.0307 0.65 150 4.1723 4.1723 0.253 0.65 222 -0.5633 0.7622 0.0453 0.75 222 -1.3411 0.5035 0.0861 0.75 234 0.7275 1.2452 0.0531 0.85 138 -1.0443 0.7502 0.0697 0.85 222 -0.5177 0.7328 0.0433 0.85 234 -0.3848 0.7386 0.0379 0.45 30 -0.2931 0.7307 0.0351 0.55 42 -0.0673 0.7294 0.0303 0.55 210 0.1323 0.6021 0.0311 0.55 234 0.1411 0.7436 0.0312 0.65 138 -0.7705 0.6929 0.0564 0.75 234 0.7208 0.6416 0.0538