CLAS physics database search results Measurement E151M2329 EG4 Xiaochao Zheng 2016 cos(theta_pi+) phi(pi+) A_LL Stat. error Syst. error degrees 0.75 102 1.4696 0.9509 0.1107 0.75 234 -0.5305 1.0077 0.0488 0.85 54 1.8379 0.8145 0.1366 0.85 222 0.4665 0.8749 0.0452 0.85 234 0.502 0.9737 0.0472 0.85 246 -0.7125 0.9153 0.0597 0.85 258 0.1103 0.8544 0.031 0.85 270 1.3441 0.7982 0.102 0.85 282 0.1306 0.9134 0.0315 0.95 270 0.7273 0.8428 0.0607 0.95 282 -1.1897 0.7048 0.0913 0.95 294 0.0764 0.8334 0.0305 0.95 306 1.5601 0.8695 0.117 0.95 318 -0.1907 0.798 0.033