Covariant Spectator Theory of $np$ scattering: Deuteron form factors

The deuteron form factors are calculated using two model wave functions obtained from the 2007 CST high precision fits to $np$ scattering data. Included in the calculation are a new class of isoscalar$np$ interaction currents which are automatically generated by the nuclear forcemodel used in these fits. If the nuclear model WJC2 is used, a precision fit ($\chi^2$/datum $\eqsim1$) to the Sick Global Analysis(GA) of all $ed$ elastic scatteringdata can be obtained by adjusting the unknown off-shell nucleon form factors $F_3(Q^2)$ (discussed before) and $F_4(Q^2)$ (introduced in this paper), and predicting the high $Q^2$ behavior of the neutron charge form factor $G_{En}(Q^2)$ well beyond the region where it has been measured directly. Relativistic corrections, isoscalarinteraction currents, and off-shell effects are defined, discussed, and their size displayed. A rationale for extending $ed$ elastic scatteringmeasurements to higher $Q^2$ is presented.