CLAS physics database search results Measurement E151M913 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 294 -0.7005 0.8141 0.0713 0.85 102 0.5432 1.067 0.0584 0.85 114 -1.4462 1.0847 0.1368 0.85 234 0.0429 1.1088 0.0303 0.65 114 0.3984 0.7209 0.0398 0.75 282 0.2972 0.6547 0.0358 0.85 102 -0.1343 0.6317 0.0313 0.85 114 0.0649 0.7025 0.0303 0.85 210 2.8283 2.8283 0.188 0.85 234 0.6947 0.7885 0.0546