CLAS physics database search results Measurement E19M21 E89-004 R. A. Schumacher 2005 cos(theta) Cx Data errors dimensionless dimensionless dimensionless -0.7 1.186 0.761 -0.4 0.134 0.515 -0.1 -0.92 0.404 0.2 -0.424 0.3 0.5 -0.312 0.203 0.8 -0.521 0.267