CLAS physics database search results Measurement E151M1170 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Stat. error Syst. error degrees 0.85 198 0.207 0.9674 0.0336 0.85 234 -0.163 0.8225 0.0323 0.95 198 0.14 0.8438 0.0317 0.95 210 2.2287 1.0084 0.1656 0.95 222 1.3075 0.9475 0.1002 0.95 234 1.2399 0.9452 0.0955