CLAS physics database search results Measurement E151M2886 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LU Stat. error Syst. error degrees 0.45 42 0.1737 0.233 0.0303 0.65 222 0.1785 0.2642 0.0302 0.85 234 0.2505 0.2583 0.0304 0.45 222 -0.3622 0.3801 0.0309 0.55 222 -0.4373 0.2937 0.0312 0.55 234 -0.2567 0.3914 0.0304 0.75 234 0.0372 0.3666 0.03 0.85 138 -0.7409 0.1918 0.0335 0.85 222 0.3301 0.307 0.0307 0.85 234 -0.2724 0.3823 0.0305