The quantum electrodynamics of two-Dirac particles system in (2+1) dimensions

In this work, in (2+1) space-time dimensions, relativistic quantum mechanical behavior of two-dirac particles system has been investigated. For general central interaction potentials between particles, set of radial differential equation has been obtained. These equations have been solved when interaction potentials between particles is zero, in the case of equal masses and in the case of different masses, and then components of spinor have been found. Under the Coulomb interaction, again for same masses and for different masses, set of radial differential equation has been solved and then energy spectrum has been obtained. Finally, relativistic two-body system in exponentially expanding flat universe model has been investigated and for this space-time metric, it's solution has been obtained.