CLAS physics database search results Measurement E19M31 E89-004 R. A. Schumacher 2005 cos(theta) Cx Data errors dimensionless dimensionless dimensionless -0.7 -0.986 1.066 -0.4 -1.042 1.022 -0.1 1.461 1.218 0.2 -0.333 1.151 0.5 0.392 0.692 0.8 -0.743 0.505