Numerical study of the three-boson bound-state problem in partial-wave and vector-variable formulations

Abstract

We present a systematic benchmark of the three-boson bound-state problem in momentum space, comparing one-dimensional (1D) spectator-amplitude, two-dimensional (2D) partial-wave, and three-dimensional (3D) vector-variable formulations. The benchmark controls the interaction representation by embedding the same finite partial-wave interaction space in each formulation, so that discrepancies reflect discretization, interpolation, and quadrature errors. This enables direct 1D--2D--3D comparisons for separable interactions, controlled 2D--3D tests for local interactions, and comparison with the full local interaction in the 3D vector-variable formulation. Binding energies agree at the $10^{-6}$~MeV level for separable interactions and at the few-$10^{-6}$ to $10^{-5}$~MeV level for local interactions. The 2D and 3D equations are also solved in both $t$-matrix-driven and bare-potential-driven forms, whose agreement validates the permutation geometry, quadrature, and interpolation. Fourier transforms to coordinate space yield consistent norm decompositions and spatial observables, providing an independent check of the momentum-space solutions.