3,175 research outputs found
Solution of Two-Body Bound State Problems with Confining Potentials
The homogeneous Lippmann-Schwinger integral equation is solved in momentum
space by using confining potentials. Since the confining potentials are
unbounded at large distances, they lead to a singularity at small momentum. In
order to remove the singularity of the kernel of the integral equation, a
regularized form of the potentials is used. As an application of the method,
the mass spectra of heavy quarkonia, mesons consisting from heavy quark and
antiquark , are calculated for linear and
quadratic confining potentials. The results are in good agreement with
configuration space and experimental results.Comment: 6 pages, 5 table
Radii in weakly-bound light halo nuclei
A systematic study of the root-mean-square distance between the constituents
of weakly-bound nuclei consisting of two halo neutrons and a core is performed
using a renormalized zero-range model. The radii are obtained from a universal
scaling function that depends on the mass ratio of the neutron and the core, as
well as on the nature of the subsystems, bound or virtual. Our calculations are
qualitatively consistent with recent data for the neutron-neutron
root-mean-square distance in the halo of Li and Be nuclei
Scaling functions of two-neutron separation energies of with finite range potentials
The behaviour of an Efimov excited state is studied within a three-body
Faddeev formalism for a general neutron-neutron-core system, where neutron-core
is bound and neutron-neutron is unbound, by considering zero-ranged as well as
finite-ranged two-body interactions. For the finite-ranged interactions we have
considered a one-term separable Yamaguchi potential. The main objective is to
study range corrections in a scaling approach, with focus in the exotic carbon
halo nucleus
Localized modes of binary mixtures of Bose-Einstein condensates in nonlinear optical lattices
The properties of the localized states of a two component Bose-Einstein
condensate confined in a nonlinear periodic potential [nonlinear optical
lattice] are investigated. We reveal the existence of new types of solitons and
study their stability by means of analytical and numerical approaches. The
symmetry properties of the localized states with respect to the NOL are also
investigated. We show that nonlinear optical lattices allow the existence of
bright soliton modes with equal symmetry in both components, bright localized
modes of mixed symmetry type, as well as, dark-bright bound states and bright
modes on periodic backgrounds. In spite of the quasi 1D nature of the problem,
the fundamental symmetric localized modes undergo a delocalizing transition
when the strength of the nonlinear optical lattice is varied. This transition
is associated with the existence of an unstable solution, which exhibits a
shrinking (decaying) behavior for slightly overcritical (undercritical)
variations in the number of atoms.Comment: 13 pages, 14 figure
Effective range from tetramer dissociation data for cesium atoms
The shifts in the four-body recombination peaks, due to an effective range
correction to the zero-range model close to the unitary limit, are obtained and
used to extract the corresponding effective range of a given atomic system. The
approach is applied to an ultracold gas of cesium atoms close to broad Feshbach
resonances, where deviations of experimental values from universal model
predictions are associated to effective range corrections. The effective range
correction is extracted, with a weighted average given by 3.9,
where is the van der Waals length scale; which is consistent with the
van der Waals potential tail for the system. The method can be generally
applied to other cold atom experimental setups to determine the contribution of
the effective range to the tetramer dissociation position.Comment: A section for two-, three- and four-boson bound state formalism is
added, accepted for publication in Phys. Rev.
Probing the Efimov discrete scaling in atom-molecule collision
The discrete Efimov scaling behavior, well-known in the low-energy spectrum
of three-body bound systems for large scattering lengths (unitary limit), is
identified in the energy dependence of atom-molecule elastic cross-section in
mass imbalanced systems. That happens in the collision of a heavy atom with
mass with a weakly-bound dimer formed by the heavy atom and a lighter one
with mass . Approaching the heavy-light unitary limit the wave
elastic cross-section will present a sequence of zeros/minima at
collision energies following closely the Efimov geometrical law. Our results
open a new perspective to detect the discrete scaling behavior from low-energy
scattering data, which is timely in view of the ongoing experiments with
ultra-cold binary mixtures having strong mass asymmetries, such as Lithium and
Caesium or Lithium and Ytterbium
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