We calculate the volume dependence of the ground-state energy of $n$ identical bosons with short-range repulsive (or weakly attractive) interactions in a periodic spatial volume of side $L$, up to and including terms of order $L^{-6}$. With this result, Lattice-QCD calculations of the ground-state energies of three or more pions will allow for a systematic extraction of the three-pion interaction at this order in the volume expansion.

• Received 2 August 2007

DOI:https://doi.org/10.1103/PhysRevD.76.074507