CLAS physics database search results Measurement E151M2411 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.75 222 0.6728 1.0124 0.0573 0.85 90 -1.248 0.959 0.0953 0.85 102 -0.2329 1.0151 0.0344 0.85 114 -0.3755 1.0638 0.0405 0.85 174 -1.2313 0.9429 0.0942 0.85 186 -0.116 0.8493 0.0312 0.85 198 -1.316 0.8362 0.1 0.85 210 0.3984 1.0219 0.0416 0.85 222 0.4998 1.0308 0.047 0.85 234 -0.2589 0.9834 0.0354