490 research outputs found
Algebraic Model for scattering in three-s-cluster systems. I. Theoretical Background
A framework to calculate two-particle matrix elements for fully
antisymmetrized three-cluster configurations is presented. The theory is
developed for a scattering situation described in terms of the Algebraic Model.
This means that the nuclear many-particle state and its asymptotic behaviour
are expanded in terms of oscillator states of the intra-cluster coordinates.
The Generating Function technique is used to optimize the calculation of matrix
elements. In order to derive the dynamical equations, a multichannel version of
the Algebraic Model is presented.Comment: 20 pages, 1 postscript figure, submitted to Phys. Rev.
Nucleon-nucleon interaction in the -matrix inverse scattering approach and few-nucleon systems
The nucleon-nucleon interaction is constructed by means of the -matrix
version of inverse scattering theory. Ambiguities of the interaction are
eliminated by postulating tridiagonal and quasi-tridiagonal forms of the
potential matrix in the oscillator basis in uncoupled and coupled waves,
respectively. The obtained interaction is very accurate in reproducing the
scattering data and deuteron properties. The interaction is used in the no-core
shell model calculations of H and He nuclei. The resulting binding
energies of H and He are very close to experimental values.Comment: Text is revised, new figures and references adde
Re-entrant spin glass and magnetoresistance in Co_{0.2}Zn_{0.8}Fe_{1.6}Ti_{0.4}O_4 spinel oxide
We have investigated the static and dynamic response of magnetic clusters in
Co_{0.2}Zn_{0.8}Fe_{1.6}Ti_{0.4}O_4 spinel oxide, where a sequence of magnetic
phase transitions, i.e., paramagnetic (PM) to ferromagnetic at T_{C}
270K and ferromagnetic to canted spin glass state at T_f\leq$ 125K is
observed
A netron halo in 8He
The structure of He is investigated within a three-cluster microscopic
model. The three-cluster configuration was used to describe
the properties of the ground state of the nucleus. The obtained results
evidently indicate the existence of a neutron halo in He.Comment: 14 pages, 6 postscript figures, submitted to Phys. Atom. Nuc
q-Functional Wick's theorems for particles with exotic statistics
In the paper we begin a description of functional methods of quantum field
theory for systems of interacting q-particles. These particles obey exotic
statistics and are the q-generalization of the colored particles which appear
in many problems of condensed matter physics, magnetism and quantum optics.
Motivated by the general ideas of standard field theory we prove the
q-functional analogues of Hori's formulation of Wick's theorems for the
different ordered q-particle creation and annihilation operators. The formulae
have the same formal expressions as fermionic and bosonic ones but differ by a
nature of fields. This allows us to derive the perturbation series for the
theory and develop analogues of standard quantum field theory constructions in
q-functional form.Comment: 15 pages, LaTeX, submitted to J.Phys.
Dimensional Reduction of Gravity and Relation between Static States, Cosmologies and Waves
We introduce generalized dimensional reductions of an integrable
1+1-dimensional dilaton gravity coupled to matter down to one-dimensional
static states (black holes in particular), cosmological models and waves. An
unusual feature of these reductions is the fact that the wave solutions depend
on two variables - space and time. They are obtained here both by reducing the
moduli space (available due to complete integrability) and by a generalized
separation of variables (applicable also to non integrable models and to higher
dimensional theories). Among these new wave-like solutions we have found a
class of solutions for which the matter fields are finite everywhere in
space-time, including infinity.
These considerations clearly demonstrate that a deep connection exists
between static states, cosmologies and waves. We argue that it should exist in
realistic higher-dimensional theories as well. Among other things we also
briefly outline the relations existing betweenthe low-dimensional models that
we have discussed hereand the realistic higher-dimensional ones.
This paper develops further some ideas already present in our previous
papers. We briefly reproduce here (without proof) their main results in a more
concise form and give an important generalization.Comment: 28 pages, Appendix and some new material in Sections 2 and Section 4
has been added, misprints corrected and some editing has been don
Statistical Origin of Pseudo-Hermitian Supersymmetry and Pseudo-Hermitian Fermions
We show that the metric operator for a pseudo-supersymmetric Hamiltonian that
has at least one negative real eigenvalue is necessarily indefinite. We
introduce pseudo-Hermitian fermion (phermion) and abnormal phermion algebras
and provide a pair of basic realizations of the algebra of N=2
pseudo-supersymmetric quantum mechanics in which pseudo-supersymmetry is
identified with either a boson-phermion or a boson-abnormal-phermion exchange
symmetry. We further establish the physical equivalence (non-equivalence) of
phermions (abnormal phermions) with ordinary fermions, describe the underlying
Lie algebras, and study multi-particle systems of abnormal phermions. The
latter provides a certain bosonization of multi-fermion systems.Comment: 20 pages, to appear in J.Phys.
Solution of the Cauchy Problem for a Time-Dependent Schoedinger Equation
We construct an explicit solution of the Cauchy initial value problem for the
n-dimensional Schroedinger equation with certain time-dependent Hamiltonian
operator of a modified oscillator. The dynamical SU(1,1) symmetry of the
harmonic oscillator wave functions, Bargmann's functions for the discrete
positive series of the irreducible representations of this group, the Fourier
integral of a weighted product of the Meixner-Pollaczek polynomials, a
Hankel-type integral transform and the hyperspherical harmonics are utilized in
order to derive the corresponding Green function. It is then generalized to a
case of the forced modified oscillator. The propagators for two models of the
relativistic oscillator are also found. An expansion formula of a plane wave in
terms of the hyperspherical harmonics and solution of certain infinite system
of ordinary differential equations are derived as a by-product.Comment: 29 pages, 4 figure
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