CLAS physics database search results Measurement E151M3094 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.85 234 -0.115 0.2614 0.0301 0.85 246 -0.2399 0.2653 0.0304 0.95 222 -0.2427 0.2655 0.0304 0.95 258 -0.3219 0.218 0.0307