title: Five-Body Efimov Effect and Universal Pentamer in Fermionic Mixtures.
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.
authors.affiliation: IPNO, CNRS/IN2P3, Univ. Paris-Sud, Université Paris-Saclay, F-91406 Orsay, France.
authors.forename: B
authors.initials: B
authors.lastname: Bazak
authors.affiliation: LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France.|Kavli Institute for Theoretical Physics, University of California, Santa Barbara, Santa Barbara, California 93106, USA.
authors.forename: D S
authors.initials: DS
authors.lastname: Petrov