title: Four-body Efimov effect for three fermions and a lighter particle.
abstract: We study three same-spin-state fermions of mass M interacting with a distinguishable particle of mass m in the unitary limit where the interaction has a zero range and an infinite s-wave scattering length. We predict an interval of mass ratio 13.384<M/m<13.607 where there exists a purely four-body Efimov effect, leading to the occurrence of weakly bound tetramers without Efimov trimers.
authors.affiliation: Laboratoire Kastler Brossel, École Normale Supérieure and CNRS, UPMC, 24 rue Lhomond, 75231 Paris, France.
authors.forename: Yvan
authors.initials: Y
authors.lastname: Castin
authors.forename: Christophe
authors.initials: C
authors.lastname: Mora
authors.forename: Ludovic
authors.initials: L
authors.lastname: Pricoupenko