Finite-volume energy shift of the three-nucleon ground state

A perturbative calculation of the three-nucleon ground-state energy shift in a finite volume is carried out within the non-relativistic effective theory. The energy shift is evaluated up to and including $\mathcal{O}(L^{-6})$, where $L$ is the size of a cubic box. The convergence of the perturbative series at physical values of the scattering lengths is studied numerically.