CLAS physics database search results Measurement E151M2899 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.75 222 0.0532 0.2833 0.03 0.75 234 -0.6751 0.2015 0.0329 0.85 222 -0.2219 0.3702 0.0303 0.85 234 -0.0646 0.4166 0.03