CLAS physics database search results Measurement E151M2035 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.75 90 0.9548 0.659 0.069 0.75 102 0.195 0.5965 0.0538 0.85 102 -1.0534 0.7217 0.0748 0.85 234 1.0879 0.8669 0.0769 0.85 258 0.3088 0.8594 0.0361 0.85 270 -0.9768 0.7473 0.0703 0.85 282 0.2019 0.8322 0.0328 0.95 306 0.3919 1.0303 0.0394 0.75 114 0.9792 1.3434 0.0949 0.75 126 -0.1175 1.3858 0.0319 0.75 258 0.4289 1.1167 0.0495 0.85 270 0.9328 1.1444 0.0908