CLAS physics database search results Measurement E151M2062 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.75 90 -0.2604 1.4517 0.0384 0.75 102 2.143 1.1474 0.1992 0.75 126 -0.4876 1.5701 0.0539 0.75 234 0.3089 1.2474 0.0413 0.75 258 -0.0692 1.1061 0.0307 0.85 258 -1.0451 1.4278 0.1006 0.85 270 -0.3198 1.2108 0.042 0.95 270 1.9738 3.9456 0.1839 0.95 282 -4.2153 3.7306 0.3886 0.95 294 -0.3456 3.1131 0.0437 0.65 102 0.1321 0.756 0.0312 0.75 114 0.5529 0.6774 0.0468 0.75 234 -0.3034 0.7185 0.0359 0.85 126 1.7253 0.7674 0.1162 0.85 234 1.6535 0.9054 0.1117 0.85 246 0.6578 0.6568 0.0523 0.85 258 0.3259 0.827 0.0367 0.85 270 0.474 0.7979 0.043 0.95 270 -0.8872 1.3034 0.065