2,523 research outputs found
The structure of the atomic helium trimers: Halos and Efimov states
The Faddeev equations for the atomic helium-trimer systems are solved
numerically with high accuracy both for the most sophisticated realistic
potentials available and for simple phenomenological potentials. An efficient
numerical procedure is described. The large-distance asymptotic behavior,
crucial for weakly bound three-body systems, is described almost analytically
for arbitrary potentials. The Efimov effect is especially considered. The
geometric structures of the bound states are quantitatively investigated. The
accuracy of the schematic models and previous computations is comparable, i.e.
within 20% for the spatially extended states and within 40% for the smaller
^4He-trimer ground state.Comment: 32 pages containing 7 figures and 6 table
The Four-Boson System with Short-Range Interactions
We consider the non-relativistic four-boson system with short-range forces
and large scattering length in an effective quantum mechanics approach. We
construct the effective interaction potential at leading order in the large
scattering length and compute the four-body binding energies using the
Yakubovsky equations. Cutoff independence of the four-body binding energies
does not require the introduction of a four-body force. This suggests that two-
and three-body interactions are sufficient to renormalize the four-body system.
We apply the equations to 4He atoms and calculate the binding energy of the 4He
tetramer. We observe a correlation between the trimer and tetramer binding
energies similar to the Tjon line in nuclear physics. Over the range of binding
energies relevant to 4He atoms, the correlation is approximately linear.Comment: 23 pages, revtex4, 5 PS figures, discussion expanded, results
unchange
Integrable magnetic geodesic flows on Lie groups
Right-invariant geodesic flows on manifolds of Lie groups associated with
2-cocycles of corresponding Lie algebras are discussed. Algebra of integrals of
motion for magnetic geodesic flows is considered and necessary and sufficient
condition of integrability in quadratures is formulated. Canonic forms for
2-cocycles of all 4-dimensional Lie algebras are given and integrable cases
among them are separated.Comment: 16 page
Non-commutative low dimension spaces and superspaces associated with contracted quantum groups and supergroups
Quantum planes which correspond to all one parameter solutions of QYBE for
the two-dimensional case of GL-groups are summarized and their geometrical
interpretations are given. It is shown that the quantum dual plane is
associated with an exotic solution of QYBE and the well-known quantum -plane
may be regarded as the quantum analog of the flag (or fiber) plane.
Contractions of the quantum supergroup and corresponding quantum
superspace are considered in Cartesian basis. The contracted
quantum superspace is interpreted as the non-commutative
analog of the superspace with the fiber odd part.Comment: Talk given at the XIII Int. Coll. on Integrable Systems and Quantum
Groups, June 17-19, 2004, Prague, Czech Republic. Submitted in Czech. J. of
Physic
Limiting Case of Modified Electroweak Model for Contracted Gauge Group
The modification of the Electroweak Model with 3-dimensional spherical
geometry in the matter fields space is suggested. The Lagrangian of this model
is given by the sum of the {\it free} (without any potential term) matter
fields Lagrangian and the standard gauge fields Lagrangian. The vector boson
masses are generated by transformation of this Lagrangian from Cartesian
coordinates to a coordinates on the sphere . The limiting case of the
bosonic part of the modified model, which corresponds to the contracted gauge
group is discussed. Within framework of the limit model
Z-boson and electromagnetic fields can be regarded as an external ones with
respect to W-bosons fields in the sence that W-boson fields do not effect on
these external fields. The masses of all particles of the Electroweak Model
remain the same, but field interactions in contracted model are more simple as
compared with the standard Electroweak Model.Comment: 12 pages, talk given at the XIII Int. Conf. on SYMMETRY METHODS IN
PHYSICS, Dubna, Russia, July 6-9, 2009; added references for introduction,
clarified motivatio
Production of three-body Efimov molecules in an optical lattice
We study the possibility of associating meta-stable Efimov trimers from three
free Bose atoms in a tight trap realised, for instance, via an optical lattice
site or a microchip. The suggested scheme for the production of these molecules
is based on magnetically tunable Feshbach resonances and takes advantage of the
Efimov effect in three-body energy spectra. Our predictions on the energy
levels and wave functions of three pairwise interacting 85Rb atoms rely upon
exact solutions of the Faddeev equations and include the tightly confining
potential of an isotropic harmonic atom trap. The magnetic field dependence of
these energy levels indicates that it is the lowest energetic Efimov trimer
state that can be associated in an adiabatic sweep of the field strength. We
show that the binding energies and spatial extents of the trimer molecules
produced are comparable, in their magnitudes, to those of the associated
diatomic Feshbach molecule. The three-body molecular state follows Efimov's
scenario when the pairwise attraction of the atoms is strengthened by tuning
the magnetic field strength.Comment: 21 pages, 8 figures (final version
Higgsless Electroweak Model and Contraction of Gauge Group
A modified formulation of the Electroweak Model with 3-dimensional spherical
geometry in the target space is suggested. The {\it free} Lagrangian in the
spherical field space along with the standard gauge field Lagrangian form the
full Higgsless Lagrangian of the model, whose second order terms reproduce the
same experimentally verified fields with the same masses as the Standard
Electroweak Model. The vector bosons masses are automatically generated, so
there is no need in special mechanism of spontaneous symmetry breaking.
The limiting case of the modified Higgsless Electroweak Model, which
corresponds to the contracted gauge group is discussed.
Within framework of the limit model Z-boson, electromagnetic and electron
fields are interpreted as an external ones with respect to W-bosons and
neutrino fields. The W-bosons and neutrino fields do not effect on these
external fields. The masses of all particles remain the same, but the field
interactions in contracted model are more simple as compared with the standard
Electroweak Model due to nullification of some terms.Comment: Talk at the International Workshop "`Supersymmetries and Quantum
Symmetries"' (SQS-09), Dubna, Russia, July 29 -- August 3, 2009, 11
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