CLAS physics database search results Measurement E151M1913 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.65 126 -0.1229 0.8591 0.0309 0.65 222 0.1861 0.8324 0.032 0.65 282 0.4523 0.7851 0.0406 0.65 294 0.8112 0.7383 0.0576 0.75 126 0.8391 0.7412 0.059 0.75 138 0.2236 0.8359 0.0329 0.75 222 -1.1745 0.7284 0.0772 0.75 234 -0.8096 0.7066 0.0575 0.85 102 0.4334 0.8023 0.0399 0.85 126 1.4684 0.7053 0.0939 0.85 210 -1.7869 0.6197 0.1124 0.85 246 0.6749 0.7481 0.0507