CLAS physics database search results Measurement E19M13 E89-004 R. A. Schumacher 2005 cos(theta) Cx Data errors dimensionless dimensionless dimensionless -0.7 -0.011 0.644 -0.4 -1 0.507 -0.1 -0.891 0.24 0.2 -0.912 0.179 0.5 -0.429 0.164 0.8 -0.745 0.253