CLAS physics database search results Measurement E151M561 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.45 78 -0.2627 0.7304 0.034 0.65 78 0.2485 0.7482 0.0336 0.65 222 -0.4004 0.6852 0.0387 0.65 234 -0.7923 0.5287 0.057 0.65 246 -0.1135 0.642 0.0308 0.75 114 0.5405 0.7934 0.0446 0.75 126 0.982 0.7181 0.0671 0.75 234 0.1353 0.7297 0.0311 0.85 138 -0.7927 0.6191 0.057 0.85 234 1.4032 0.6381 0.0909 0.85 246 1.3403 0.6477 0.0873