CLAS physics database search results Measurement E151M827 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 90 -0.0926 1.0533 0.0312 0.95 306 1.1217 2.8828 0.1078 0.65 114 -0.2998 0.6971 0.0359 0.75 90 -0.1359 0.6729 0.0313 0.75 270 -0.6651 0.5949 0.053 0.85 222 0.441 0.842 0.0417 0.85 234 0.3344 0.7517 0.0372 0.85 258 1.3997 0.7247 0.0966 0.85 282 1.6856 0.7197 0.1146 0.95 294 1.6304 1.1485 0.1111