CLAS physics database search results Measurement E151M2063 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.75 90 -0.8587 0.684 0.0634 0.75 102 0.4308 0.7265 0.0411 0.75 246 0.2324 0.8037 0.0336 0.85 234 0.8414 0.8582 0.0624 0.85 246 0.2304 0.7857 0.0335 0.85 270 -0.1073 0.7767 0.0308 0.95 282 1.6053 1.1026 0.1087 0.65 114 0.6999 1.344 0.071 0.75 246 0.3352 1.2916 0.043 0.85 66 1.5047 1.6348 0.1415 0.85 114 -5.2456 5.2456 0.483 0.85 258 -0.0186 1.3347 0.03 0.85 282 2.1357 1.2243 0.1986