CLAS physics database search results Measurement E151M1473 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.75 114 -0.37 0.7276 0.0373 0.85 102 -0.6506 0.7077 0.0492 0.55 270 -1.104 1.0701 0.0709 0.85 102 0.7428 0.9695 0.0526 0.85 114 1.0956 1.265 0.0704 0.85 150 1.4717 0.661 0.0907 0.85 270 1.4316 0.5798 0.0885 0.85 294 -1.0898 0.7865 0.0701 0.95 138 -0.9353 0.7169 0.0621