CLAS physics database search results Measurement E151M499 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_UL Data errors Systematic errors degrees 0.45 294 -0.5052 0.52 0.0431 0.65 282 0.2359 0.6216 0.0333 0.65 294 -0.3556 0.4708 0.0371 0.75 66 0.4605 0.6405 0.0412 0.75 78 0.2785 0.6126 0.0345 0.75 90 0.6749 0.612 0.051 0.75 102 0.1476 0.5428 0.0313 0.75 294 -0.3672 0.4463 0.0375 0.85 102 0.831 0.6433 0.059 0.85 234 0.9741 0.6542 0.0667 0.85 258 -0.216 0.4682 0.0328 0.85 282 -0.7569 0.4246 0.0552 0.85 294 0.102 0.4715 0.0306 0.95 78 0.3176 0.5737 0.0357