CLAS physics database search results Measurement E19M2 E89-004 R. A. Schumacher 2005 cos(theta) Cz Data errors dimensionless dimensionless dimensionless -0.7 0 0 -0.4 0.689 0.519 -0.1 1.477 0.347 0.2 0.76 0.301 0.5 1.391 0.302 0.8 1.334 0.383