CLAS physics database search results Measurement E151M1997 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.85 246 -1.1639 1.6504 0.1111 0.75 258 0.0214 0.6392 0.03 0.85 78 0.2499 0.6772 0.0341 0.85 102 1.2776 0.6983 0.0884 0.85 270 0.0982 0.697 0.0307 0.85 294 -0.4416 0.5596 0.0415