Effect of negative energy components for two-nucleon systems in the relativistic framework with the separable ansatz

We investigate the electromagnetic properties of the deuteron such as the charge and magnetic form factors by solving the Bethe-Salpeter equation (BSE) with the separable ansatz. In solving the deuteron bound state solution to the BSE, we include negative energy components of $P$-wave in addition to the $^3S_1$ and $^3D_1$ states of positive energy, employing a rank IV separable ansatz. We found that the inclusion of the negative energy components improves systematically the electromagnetic properties which are not described in the conventional non-relativistic impulse approximation.