2,171 research outputs found
Effective Range Corrections to Three-Body Recombination for Atoms with Large Scattering Length
Few-body systems with large scattering length a have universal properties
that do not depend on the details of their interactions at short distances. The
rate constant for three-body recombination of bosonic atoms of mass m into a
shallow dimer scales as \hbar a^4/m times a log-periodic function of the
scattering length. We calculate the leading and subleading corrections to the
rate constant which are due to the effective range of the atoms and study the
correlation between the rate constant and the atom-dimer scattering length. Our
results are applied to 4He atoms as a test case.Comment: 6 pages, 2 figures, improved discussion, final versio
Resonant Dimer Relaxation in Cold Atoms with a Large Scattering Length
Efimov physics refers to universal phenomena associated with a discrete
scaling symmetry in the 3-body problem with a large scattering length. The
first experimental evidence for Efimov physics was the recent observation of a
resonant peak in the 3-body recombination rate for 133Cs atoms with large
negative scattering length. There can also be resonant peaks in the atom-dimer
relaxation rate for large positive scattering length. We calculate the
atom-dimer relaxation rate as a function of temperature and show how
measurements of the relaxation rate can be used to determine accurately the
parameters that govern Efimov physics.Comment: 4 pages, 2 eps figures, normalization error in figures corrected,
equations unchange
The Efimov effect for three interacting bosonic dipoles
Three oriented bosonic dipoles are treated using the hyperspherical adiabatic
representation, providing numerical evidence that the Efimov effect persists
near a two-dipole resonance and in a system where angular momentum is not
conserved. Our results further show that the Efimov features in scattering
observables become universal, with a known three-body parameter, i.e. the
resonance energies depend only on the two-body physics, which also has
implications for the universal spectrum of the four-dipole problem. Moreover,
the Efimov states should be long-lived, which is favorable for their creation
and manipulation in ultracold dipolar gases. Finally, deeply-bound two-dipole
states are shown to be relatively stable against collisions with a third
dipole, owing to the emergence of a repulsive interaction originating in the
angular momentum nonconservation for this system.Comment: 4 pages, 2 figures, 1 tabl
The few-body problem for trapped bosons with large scattering length
We calculate energy levels of two and three bosons trapped in a harmonic
oscillator potential with oscillator length . The atoms are
assumed to interact through a short-range potential with a scattering length
, and the short-distance behavior of the three-body wave function is
characterized by a parameter . For large positive ,
the energies of states which, in the absence of the trap, correspond to three
free atoms approach values independent of and . For other states
the dependence of the energy is strong, but the energy is independent
of for .Comment: 4 pages, 3 figure
Origin of the Three-body Parameter Universality in Efimov Physics
In recent years extensive theoretical and experimental studies of universal
few-body physics have led to advances in our understanding of universal Efimov
physics [1]. The Efimov effect, once considered a mysterious and esoteric
effect, is today a reality that many experiments in ultracold quantum gases
have successfully observed and continued to explore [2-14]. Whereas theory was
the driving force behind our understanding of Efimov physics for decades,
recent experiments have contributed an unexpected discovery. Specifically,
measurements have found that the so-called three-body parameter determining
several properties of the system is universal, even though fundamental
assumptions in the theory of the Efimov effect suggest that it should be a
variable property that depends on the precise details of the short-range two-
and three-body interactions. The present Letter resolves this apparent
contradiction by elucidating unanticipated implications of the two-body
interactions. Our study shows that the three-body parameter universality
emerges because a universal effective barrier in the three-body potentials
prevents the three particles from simultaneously getting close to each other.
Our results also show limitations on this universality, as it is more likely to
occur for neutral atoms and less likely to extend to light nuclei.Comment: 11 pages; 9 figures. Includes Supplementary Materia
(Anti-)self-dual homogeneous vacuum gluon field as an origin of confinement and symmetry breaking in QCD
It is shown that an (anti-)self-dual homogeneous vacuum gluon field appears
in a natural way within the problem of calculation of the QCD partition
function in the form of Euclidean functional integral with periodic boundary
conditions. There is no violation of cluster property within this formulation,
nor are parity, color and rotational symmetries broken explicitly. The massless
limit of the product of the quark masses and condensates, , is calculated to all loop orders. This quantity
does not vanish and is proportional to the gluon condensate appearing due to
the nonzero strength of the vacuum gluon field. We conclude that the gluon
condensate can be considered as an order parameter both for confinement and
chiral symmetry breaking.Comment: 16 pages, LaTe
Enhanced Dimer Relaxation in an Atomic/Molecular BEC
We derive a universal formula for the rate constant \beta for relaxation of a
shallow dimer into deeply-bound diatomic molecules in the case of atoms with a
large scattering length a. We show that \beta is determined by a and by two
3-body parameters that also determine the binding energies and widths of Efimov
states. The rate constant \beta scales like \hbar a/m near the resonance, but
the coefficient is a periodic function of ln(a) that may have resonant
enhancement at values of a that differ by multiples of 22.7.Comment: 5 pages, revtex4, 2 PS figures, title changed, final versio
Universality in the physics of cold atoms with large scattering length
Effective field theories exploit a separation of scales in physical systems
in order to perform systematically improvable, model-independent calculations.
They are ideally suited to describe universal aspects of a wide range of
physical systems. I will discuss recent applications of effective field theory
to cold atomic and molecular few-body systems with large scattering length.Comment: Invited talk at Few-Body 17, June 2003, Durham, NC, USA, 5 pages, 3
figures, uses espcrc1.st
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