Bound-State Scalar Form Factor for Two Fermions within the Relativistic Quasipotential Approach

A new expression for the bound-state scalar form factor was obtained for two relativistic fermions of equal mass. The respective analysis was performed within the relativistic quasipotential approach based on the covariant Hamiltonian formulation of quantum field theory by means of the transition to the three-dimensional relativistic configuration representation for the interaction of two relativistic particles that have a spin of 1/2 and equal masses.