Enhanced Binding of an N-particle System Interacting with a Scalar Field II. Relativistic Version

An enhanced binding of N relativistic particles coupled to a massless scalar Bose field is investigated. It is not assumed that the system has a ground state for the zero-coupling. It is shown, however, that there exists a ground state for sufficiently large coupling. The proof is based on checking the stability condition and showing uniform exponential decay of infrared-regularized ground states.