CLAS physics database search results Measurement E151M2379 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.85 78 -0.063 1.0216 0.0303 0.85 90 -0.4437 0.9883 0.044 0.85 210 -0.0741 0.9867 0.0305 0.85 234 1.6799 0.8881 0.1255 0.85 246 0.3338 0.9746 0.0385 0.95 186 0.1558 1.0449 0.0321 0.95 198 -2.3318 0.7201 0.1717 0.95 210 1.7624 0.9015 0.1313 0.95 222 0.2907 0.989 0.0367 0.95 234 1.2227 0.9231 0.0936 0.95 246 -0.8143 0.8575 0.0662 0.95 258 -0.3064 0.8732 0.0373 0.95 282 0.3742 0.9471 0.0404