CLAS physics database search results Measurement E151M2113 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.85 234 1.309 0.8266 0.124 0.75 126 -1.2239 0.8851 0.0851 0.85 78 -1.1157 0.8543 0.0785 0.85 222 0.1182 1.0264 0.031 0.85 234 -1.794 0.8518 0.1205 0.85 246 -0.5454 0.9513 0.0465 0.85 258 -1.4334 0.9075 0.098 0.95 246 2.7649 1.277 0.1823 0.95 258 1.579 1.2285 0.107