Five-Body Efimov Effect and Universal Pentamer in Fermionic Mixtures

TL;DR

This paper predicts a five-body Efimov effect and universal pentamer states in fermionic mixtures with specific mass ratios, revealing new few-body phenomena and the influence of interaction range corrections.

Contribution

It introduces the prediction of the five-body Efimov effect in a 4+1 fermionic system and calculates energies of universal pentamer states, extending known few-body physics.

Findings

Five-body Efimov effect occurs at mass ratio 13.279(2).

Universal 4+1 pentamer states exist below Efimov thresholds.

Effective-range corrections significantly influence binding tendencies.

Abstract

We show that four heavy fermions interacting resonantly with a lighter atom (4+1 system) become Efimovian at mass ratio 13.279(2), which is smaller than the corresponding 2+1 and 3+1 thresholds. We thus predict the five-body Efimov effect for this system in the regime where any of its subsystem is non- Efimovian. For smaller mass ratios we show the existence and calculate the energy of a universal 4+1 pentamer state, which continues the series of the 2+1 trimer predicted by Kartavtsev and Malykh and 3+1 tetramer discovered by Blume. We also show that the effective-range correction for the light-heavy interaction has a strong effect on all these states and larger effective ranges increase their tendency to bind.