112 research outputs found
Exact Solutions of the Duffin Kemmer Petiau Equation for the Deformed Hulthen Potential
Using the Nikiforov Uvarov method, an application of the relativistic Duffin
Kemmer Petiau equation in the presence of a deformed Hulthen potential is
presented for spin zero particles. We derived the first order coupled
differential radial equations which enable the energy eigenvalues as well as
the full wavefunctions to be evaluated by using of the Nikiforov Uvarov method
that can be written in terms of the hypergeometric polynomials.Comment: 8 pages. submitted to Physica Script
Wither the sliding Luttinger liquid phase in the planar pyrochlore
Using series expansion based on the flow equation method we study the zero
temperature properties of the spin-1/2 planar pyrochlore antiferromagnet in the
limit of strong diagonal coupling. Starting from the limit of decoupled crossed
dimers we analyze the evolution of the ground state energy and the elementary
triplet excitations in terms of two coupling constants describing the inter
dimer exchange. In the limit of weakly coupled spin-1/2 chains we find that the
fully frustrated inter chain coupling is critical, forcing a dimer phase which
adiabatically connects to the state of isolated dimers. This result is
consistent with findings by O. Starykh, A. Furusaki and L. Balents (Phys. Rev.
B 72, 094416 (2005)) which is inconsistent with a two-dimensional sliding
Luttinger liquid phase at finite inter chain coupling.Comment: 6 pages, 4 Postscript figures, 1 tabl
Lattice vs. continuum theory of the periodic Heisenberg chain
We consider the detailed structure of low energy excitations in the periodic
spin-1/2 XXZ Heisenberg chain. By performing a perturbative calculation of the
non-linear corrections to the Gaussian model, we determine the exact
coefficients of asymptotic expansions in inverse powers of the system length N
for a large number of low-lying excited energy levels. This allows us to
calculate eigenenergies of the lattice model up to order order N^-4, without
having to solve the Bethe Ansatz equations. At the same time, it is possible to
express the exact eigenstates of the lattice model in terms of bosonic modes.Comment: 17 pages, 8 Figures. The latest version can be found at
http://www.physik.uni-kl.de/eggert/papers/index.htm
On the thermodynamic limit of form factors in the massless XXZ Heisenberg chain
We consider the problem of computing form factors of the massless XXZ
Heisenberg spin-1/2 chain in a magnetic field in the (thermodynamic) limit
where the size M of the chain becomes large. For that purpose, we take the
particular example of the matrix element of the third component of spin between
the ground state and an excited state with one particle and one hole located at
the opposite ends of the Fermi interval (umklapp-type term). We exhibit its
power-law decrease in terms of the size of the chain M, and compute the
corresponding exponent and amplitude. As a consequence, we show that this form
factor is directly related to the amplitude of the leading oscillating term in
the long-distance asymptotic expansion of the two-point correlation function of
the third component of spin.Comment: 28 page
axial form factor from bubble chamber experiments
A careful reanalysis of both Argonne National Laboratory and Brookhaven
National Laboratory data for weak single pion production is done. We consider
deuteron nuclear effects and normalization (flux) uncertainties in both
experiments. We demonstrate that these two sets of data are in good agreement.
For the dipole parametrization of , we obtain , GeV. As an application we present the discussion of
the uncertainty of the neutral current 1 production cross section,
important for the T2K neutrino oscillation experiment.Comment: 16 pages, 8 figures, 2 table
Algebraic approach to the Hulthen potential
In this paper the energy eigenvalues and the corresponding eigenfunctions are
calculated for Hulthen potential. Then we obtain the ladder operators and show
that these operators satisfy SU(2) commutation relation.Comment: 8 Pages, 1 Tabl
Model-Independent Sum Rule Analysis Based on Limited-Range Spectral Data
Partial sum rules are widely used in physics to separate low- and high-energy
degrees of freedom of complex dynamical systems. Their application, though, is
challenged in practice by the always finite spectrometer bandwidth and is often
performed using risky model-dependent extrapolations. We show that, given
spectra of the real and imaginary parts of any causal frequency-dependent
response function (for example, optical conductivity, magnetic susceptibility,
acoustical impedance etc.) in a limited range, the sum-rule integral from zero
to a certain cutoff frequency inside this range can be safely derived using
only the Kramers-Kronig dispersion relations without any extra model
assumptions. This implies that experimental techniques providing both active
and reactive response components independently, such as spectroscopic
ellipsometry in optics, allow an extrapolation-independent determination of
spectral weight 'hidden' below the lowest accessible frequency.Comment: 5 pages, 3 figure
Antiferromagnetic S=1/2 Heisenberg Chain and the Two-flavor Massless Schwinger Model
An antiferromagnetic S=1/2 Heisenberg chain is mapped to the two-flavor
massless Schwinger model at \theta=\pi. The electromagnetic coupling constant
and velocity of light in the Schwinger model are determined in terms of the
Heisenberg coupling and lattice spacing in the spin chain system.Comment: 3 pages. LaTex2
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