CLAS physics database search results Measurement E19M19 E89-004 R. A. Schumacher 2005 cos(theta) Cx Data errors dimensionless dimensionless dimensionless -0.7 -0.019 0.457 -0.4 -0.535 0.438 -0.1 -0.405 0.332 0.2 -0.507 0.214 0.5 -0.029 0.183 0.8 0.002 0.209