Itaru Sasaki Ground State of a Model in the Relativistic Quantum Electrodynamics with a Fixed Total Momentum (209K, pdf) ABSTRACT. We consider the polaron model of the relativistic quantum electrodynamics with a fixed total momentum. We analyze some properties of the ground state energy of the model, and show that the polaron model has a ground state under a condition which includes conditions for an infrared and an ultraviolet cutoff for photon momenta. In particular, we show that the model with zero total momentum, a nonzero mass of the electron and an infrared cutoff has a ground state.