CLAS physics database search results Measurement E151M1244 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.45 54 -0.0708 0.6217 0.031 0.55 246 -0.8792 0.451 0.1036 0.55 258 -0.137 0.3865 0.0337 0.55 270 -0.091 0.3758 0.0317 0.65 162 -0.144 0.6465 0.0341 0.65 186 -0.4409 0.5883 0.0581 0.65 234 -0.2482 0.4999 0.041 0.65 246 -0.0769 0.3831 0.0312 0.65 258 -0.1889 0.3396 0.0368 0.65 270 -0.1027 0.4448 0.0322 0.75 162 0.5015 0.5718 0.064 0.75 174 -0.2783 0.5113 0.0434 0.75 186 -0.0966 0.6195 0.0319 0.75 198 -0.3175 0.6485 0.0467 0.75 210 -1.0691 0.5245 0.1243 0.75 234 -0.0175 0.4504 0.0301 0.75 246 0.0316 0.4112 0.0302 0.75 258 -0.2794 0.3934 0.0435 0.75 270 0.1542 0.513 0.0347 0.85 174 0.6251 0.577 0.0766