. The meson-neutron scattering length can become infinitely large when extrapolated to an unphysical region of the quark mass between strangeness and charm in the so-called zero coupling limit. Using a low-energy cluster effective field theory, we demonstrate that the Efimov effect is formally manifest in the three-body system when the meson-neutron scattering length approaches the unitary limit of the two-body interaction. We thereby discuss the consequence of remnant universal physics in the physical

{K}^{\ensuremath{-}}nn

and

{D}^{0}nn

systems.

DOI: 10.1103/physrevc.98.034002

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We investigate the

s

-wave three-body system of two neutrons and one flavored meson with total spin-isospin

J=0,I=3/2

{K}^{\ensuremath{-}}nn

and

{D}^{0}nn

systems.

We investigate the

s

-wave three-body system of two neutrons and one flavored meson with total spin-isospin

J=0,I=3/2

. The meson-neutron scattering length can become infinitely large in an unphysical region of the quark mass when extrapolated from strangeness to charm in the so-called zero coupling limit. Using a low-energy cluster effective field theory, we demonstrate that the Efimov effect is manifest in the three-body system when the meson-neutron scattering length is extrapolated to the unitary limit of the two-body interaction. We thereby discuss the consequence of universal physics in the physical

K^{-}nn

and

D^{0}nn

systems.

Equal mass fermionic trimers with two different spin components near the unitary limit are shown to possess a universal van der Waals bound or resonance state near

s

-wave unitarity, when

p

-wave interactions are included between the particles with equal spin. Our treatment uses a single-channel Lennard-Jones interaction with long-range two-body van der Waals potentials. While it is well known that there is no true Efimov effect that would produce an infinite number of bound states in the unitary limit, we demonstrate that another type of universality emerges for the symmetry ${L}^{\mathrm{\ensuremath{\Pi}}}={1}^{\ensuremath{-}}$. The universality is a remnant of Efimov physics that exists in this system at

p

-wave unitarity, and it leads to modified threshold and scaling laws in that limit. Application of our model to the system of three lithium atoms studied experimentally by Du et al. [Phys. Rev. Lett. 102, 250402 (2009)] provides an interpretation of their measured three-body recombination loss rates.

We study two species of particles in two dimensions interacting by isotropic short-range potentials with the interspecies potential fine-tuned to a

p

-wave resonance. Their universal low-energy physics can be extracted by analyzing a properly constructed low-energy effective field theory with the renormalization group method. Consequently, a three-body system consisting of two particles of one species and one of the other is shown to exhibit the super Efimov effect, the emergence of an infinite tower of three-body bound states with orbital angular momentum $\ensuremath{\ell}=\ifmmode\pm\else\textpm\fi{}1$ whose binding energies obey a doubly exponential scaling, when the two particles are heavier than the other by a mass ratio greater than 4.034 04 for identical bosons and 2.414 21 for identical fermions. With increasing the mass ratio, the super Efimov spectrum becomes denser which would make its experimental observation easier. We also point out that the Born-Oppenheimer approximation is incapable of reproducing the super Efimov effect, the universal low-energy asymptotic scaling of the spectrum.