Relativistic N-particle energy shift in finite volume

A bstract We present a general method for deriving the energy shift of an interacting system N spinless particles in finite volume. To this end, we use nonrelativistic effective field theory (NREFT), and match pertinent low-energy constants to scattering amplitudes. Relativistic corrections are explicitly included up given order 1/ L expansion. apply obtain ground state particles, first excited two three ? 6 terms threshold parameters two- three-particle relativistic these expressions analyze -particle complex ? 4 theory.