CLAS physics database search results Measurement E151M751 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 258 2.8701 1.509 0.2666 0.85 246 -0.323 1.6442 0.0423 0.65 258 1.5465 0.4992 0.1058 0.75 258 0.1737 0.5158 0.0321 0.75 270 -0.8342 0.3526 0.0624 0.85 114 0.9215 0.6213 0.0675 0.85 126 0.6101 0.6538 0.05 0.85 258 0.2397 0.5864 0.0339 0.85 270 -0.003 0.5734 0.03