CLAS physics database search results Measurement E19M7 E89-004 R. A. Schumacher 2005 cos(theta) Cx Data errors dimensionless dimensionless dimensionless -0.7 -1.622 0.693 -0.4 -0.131 0.238 -0.1 -0.02 0.156 0.2 -0.227 0.134 0.5 -0.41 0.14 0.8 -0.309 0.218