Universality for Three Bosons with Large, Negative Effective Range: Aspects and Addenda

Resummed-Range Effective Field Theory is the consistent non-relativistic Effective Field Theory of point interactions in systems with large two-body scattering length $a$ and an effective range $r_0$ large in magnitude but negative. Its leading order is non-perturbative, and its observables depend only on the dimensionless ratio $\xi:=2r_0/a$ once $|r_0|$ is chosen as base unit. This presentation highlights aspects for three identical spinless bosons and adds details to a previous discussion [1]. At leading order, no three-body interaction is needed. A ground state exists only in the range $0.366\ldots\ge\xi\ge-8.72\ldots$, and excited states display self-similarity and Discrete Scale Invariance, with small corrections for nonzero $r_0$.