Study of virtual annihilation and retardation effects in relativistic two-, four-, and six-body wave equations in scalar QFT

The variational method within the Hamiltonianformalism of QFT using Darewych reformulated modelhas been used for scalar particles and antiparticlesinteracting through a scalar mediating field. We haveinvestigated the relativistic effects such as virtual annihilationinteractions and retardation effects for relativistictwo-, four-, and six-body wave equations inscalar QFT. Approximate ground-state solutions havebeen studied for different strengths of coupling, for bothmassive and massless mediating fields where the virtualannihilation terms or retardation effects in the waveequations have been included or eliminated.