6,983 research outputs found
Mixed Quantum/Classical Approach for Description of Molecular Collisions in Astrophysical Environments
An efficient and accurate mixed quantum/classical theory approach for computational treatment of inelastic scattering is extended to describe collision of an atom with a general asymmetric-top rotor polyatomic molecule. Quantum mechanics, employed to describe transitions between the internal states of the molecule, and classical mechanics, employed for description of scattering of the atom, are used in a self-consistent manner. Such calculations for rotational excitation of HCOOCH3 in collisions with He produce accurate results at scattering energies above 15 cm–1, although resonances near threshold, below 5 cm–1, cannot be reproduced. Importantly, the method remains computationally affordable at high scattering energies (here up to 1000 cm–1), which enables calculations for larger molecules and at higher collision energies than was possible previously with the standard full-quantum approach. Theoretical prediction of inelastic cross sections for a number of complex organic molecules observed in space becomes feasible using this new computational tool
Towards the assignment for the meson nonet
The strong decays of the , , ,
, and as the quark-antiquark states are
investigated in the framework of the meson decay model. It is found
that the , , and appear to be the
convincing states while the assignment of the
and as the isoscalar states is not favored by their
widths. In the presence of the , , and
being the members of the meson nonet, the kaon is
phenomenologically determined to has a mass of about 2153 MeV. The width of
this unobserved kaon is expected to be about 197 MeV in the decay
model.Comment: 15 pages, 5 figures, version accepted for publication in Physical
Review
Classification of All Poisson-Lie Structures on an Infinite-Dimensional Jet Group
A local classification of all Poisson-Lie structures on an
infinite-dimensional group of formal power series is given. All
Lie bialgebra structures on the Lie algebra {\Cal G}_{\infty} of
are also classified.Comment: 11 pages, AmSTeX fil
Effect of external magnetic field on electron spin dephasing induced by hyperfine interaction in quantum dots
We investigate the influence of an external magnetic field on spin phase
relaxation of single electrons in semiconductor quantum dots induced by the
hyperfine interaction. The basic decay mechanism is attributed to the
dispersion of local effective nuclear fields over the ensemble of quantum dots.
The characteristics of electron spin dephasing is analyzed by taking an average
over the nuclear spin distribution. We find that the dephasing rate can be
estimated as a spin precession frequency caused primarily by the mean value of
the local nuclear magnetic field. Furthermore, it is shown that the hyperfine
interaction does not fully depolarize electron spin. The loss of initial spin
polarization during the dephasing process depends strongly on the external
magnetic field, leading to the possibility of effective suppression of this
mechanism.Comment: 10 pages, 2 figure
Persistent current noise and electron-electron interactions
We analyze fluctuations of persistent current (PC) produced by a charged
quantum particle moving in a ring and interacting with a dissipative
environment formed by diffusive electron gas. We demonstrate that in the
presence of interactions such PC fluctuations persist down to zero temperature.
In the case of weak interactions and/or sufficiently small values of the ring
radius PC noise remains coherent and can be tuned by external magnetic flux
piercing the ring. In the opposite limit of strong interactions and/or
large values of fluctuations in the electronic bath strongly suppress
quantum coherence of the particle down to and induce incoherent
-independent current noise in the ring which persists even at
when the average PC is absent.Comment: 12 pages, 8 figure
Hamiltonian structures of fermionic two-dimensional Toda lattice hierarchies
By exhibiting the corresponding Lax pair representations we propose a wide
class of integrable two-dimensional (2D) fermionic Toda lattice (TL)
hierarchies which includes the 2D N=(2|2) and N=(0|2) supersymmetric TL
hierarchies as particular cases. We develop the generalized graded R-matrix
formalism using the generalized graded bracket on the space of graded operators
with involution generalizing the graded commutator in superalgebras, which
allows one to describe these hierarchies in the framework of the Hamiltonian
formalism and construct their first two Hamiltonian structures. The first
Hamiltonian structure is obtained for both bosonic and fermionic Lax operators
while the second Hamiltonian structure is established for bosonic Lax operators
only.Comment: 12 pages, LaTeX, the talks delivered at the International Workshop on
Classical and Quantum Integrable Systems (Dubna, January 24 - 28, 2005) and
International Conference on Theoretical Physics (Moscow, April 11 - 16, 2005
- …