CLAS physics database search results Measurement E19M3 E89-004 R. A. Schumacher 2005 cos(theta) Cx Data errors dimensionless dimensionless dimensionless -0.7 0 0 -0.4 -1.045 0.335 -0.1 -0.963 0.226 0.2 -0.563 0.193 0.5 -0.756 0.192 0.8 -0.077 0.277