CLAS physics database search results Measurement E151M1347 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.55 42 0.4311 0.9174 0.0571 0.55 54 -0.7543 0.8634 0.0902 0.55 222 -0.8992 0.8813 0.1058 0.55 234 -0.3476 0.6939 0.0494 0.55 246 0.9265 0.8383 0.1087 0.65 54 -0.7316 0.8397 0.0878 0.65 222 0.9633 0.8534 0.1127 0.65 234 0.3435 0.77 0.049 0.65 246 -0.3176 0.7547 0.0467 0.75 222 0.7079 0.7173 0.0853 0.75 234 -0.9801 0.762 0.1145 0.75 246 -0.6274 0.8219 0.0769 0.85 234 1.1881 0.8113 0.1373 0.85 246 0.4928 0.8487 0.0632