CLAS physics database search results Measurement E151M802 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.75 150 0.0822 0.8441 0.0305 0.75 234 -0.7653 0.692 0.0585 0.85 222 1.3708 0.8863 0.0948 0.85 246 1.2146 0.8268 0.0852 0.65 234 0.3678 1.0476 0.0453