CLAS physics database search results Measurement E151M1914 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.55 126 -0.1299 0.9056 0.031 0.65 114 0.1995 0.8712 0.0323 0.65 294 -1.4466 0.6867 0.0927 0.75 222 0.4193 0.6977 0.0393 0.75 234 -0.2597 0.8598 0.0339 0.75 282 0.9189 0.7413 0.0633 0.85 90 -0.4278 0.8507 0.0396 0.85 102 -0.1806 0.8053 0.0319 0.85 210 1.2759 0.6298 0.0829 0.85 234 -0.5777 0.7352 0.0461 0.95 234 1.0573 0.6967 0.0707