37,255 research outputs found
On a generalization of Jacobi's elliptic functions and the Double Sine-Gordon kink chain
A generalization of Jacobi's elliptic functions is introduced as inversions
of hyperelliptic integrals. We discuss the special properties of these
functions, present addition theorems and give a list of indefinite integrals.
As a physical application we show that periodic kink solutions (kink chains) of
the double sine-Gordon model can be described in a canonical form in terms of
generalized Jacobi functions.Comment: 18 pages, 9 figures, 3 table
Exotic magnetism on the quasi-FCC lattices of the double perovskites LaNaBO (B Ru, Os)
We find evidence for long-range and short-range ( 70 \AA~at 4 K)
incommensurate magnetic order on the quasi-face-centered-cubic (FCC) lattices
of the monoclinic double perovskites LaNaRuO and LaNaOsO
respectively. Incommensurate magnetic order on the FCC lattice has not been
predicted by mean field theory, but may arise via a delicate balance of
inequivalent nearest neighbour and next nearest neighbour exchange
interactions. In the Ru system with long-range order, inelastic neutron
scattering also reveals a spin gap 2.75 meV. Magnetic
anisotropy is generally minimized in the more familiar octahedrally-coordinated
systems, so the large gap observed for LaNaRuO may result from
the significantly enhanced value of spin-orbit coupling in this
material.Comment: 5 pages, 4 figure
Time dependent transformations in deformation quantization
We study the action of time dependent canonical and coordinate
transformations in phase space quantum mechanics. We extend the covariant
formulation of the theory by providing a formalism that is fully invariant
under both standard and time dependent coordinate transformations. This result
considerably enlarges the set of possible phase space representations of
quantum mechanics and makes it possible to construct a causal representation
for the distributional sector of Wigner quantum mechanics.Comment: 16 pages, to appear in the J. Math. Phy
Rodrigues Formula for the Nonsymmetric Multivariable Laguerre Polynomial
Extending a method developed by Takamura and Takano, we present the Rodrigues
formula for the nonsymmetric multivariable Laguerre polynomials which form the
orthogonal basis for the -type Calogero model with distinguishable
particles. Our construction makes it possible for the first time to
algebraically generate all the nonsymmetric multivariable Laguerre polynomials
with different parities for each variable.Comment: 6 pages, LaTe
Complete Set of Polarization Transfer Observables for the Reaction at 296 MeV and 0
A complete set of polarization transfer observables has been measured for the
reaction at and . The total spin transfer and the observable
deduced from the measured polarization transfer observables indicate that
the spin--dipole resonance at has greater
strength than strength, which is consistent with recent experimental and
theoretical studies. The results also indicate a predominance of the spin-flip
and unnatural-parity transition strength in the continuum. The exchange tensor
interaction at a large momentum transfer of is
discussed.Comment: 4 pages, 4 figure
Accurate black hole evolutions by fourth-order numerical relativity
We present techniques for successfully performing numerical relativity
simulations of binary black holes with fourth-order accuracy. Our simulations
are based on a new coding framework which currently supports higher order
finite differencing for the BSSN formulation of Einstein's equations, but which
is designed to be readily applicable to a broad class of formulations. We apply
our techniques to a standard set of numerical relativity test problems,
demonstrating the fourth-order accuracy of the solutions. Finally we apply our
approach to binary black hole head-on collisions, calculating the waveforms of
gravitational radiation generated and demonstrating significant improvements in
waveform accuracy over second-order methods with typically achievable numerical
resolution.Comment: 17 pages, 25 figure
Generalized Weyl-Wigner map and Vey quantum mechanics
The Weyl-Wigner map yields the entire structure of Moyal quantum mechanics
directly from the standard operator formulation. The covariant generalization
of Moyal theory, also known as Vey quantum mechanics, was presented in the
literature many years ago. However, a derivation of the formalism directly from
standard operator quantum mechanics, clarifying the relation between the two
formulations is still missing. In this paper we present a covariant
generalization of the Weyl order prescription and of the Weyl-Wigner map and
use them to derive Vey quantum mechanics directly from the standard operator
formulation. The procedure displays some interesting features: it yields all
the key ingredients and provides a more straightforward interpretation of the
Vey theory including a direct implementation of unitary operator
transformations as phase space coordinate transformations in the Vey idiom.
These features are illustrated through a simple example.Comment: 15 pages, LaTe
Exact solutions for a class of integrable Henon-Heiles-type systems
We study the exact solutions of a class of integrable Henon-Heiles-type
systems (according to the analysis of Bountis et al. (1982)). These solutions
are expressed in terms of two-dimensional Kleinian functions. Special periodic
solutions are expressed in terms of the well-known Weierstrass function. We
extend some of our results to a generalized Henon-Heiles-type system with n+1
degrees of freedom.Comment: RevTeX4-1, 13 pages, Submitted to J. Math. Phy
Antiferromagnetic Order in MnO Spherical Nanoparticles
We have performed unpolarized and polarized neutron diffraction experiments
on monodisperse 8 nm and 13 nm antiferromagnetic MnO nanoparticles. For the 8
nm sample, the antiferromagnetic transition temperature (114 K) is
suppressed compared to the bulk material (119 K) while for the 13 nm sample
(120 K) is comparable to the bulk. The neutron diffraction data of the
nanoparticles is well described using the bulk MnO magnetic structure but with
a substantially reduced average magnetic moment of 4.20.3 /Mn for
the 8 nm sample and 3.90.2 /Mn for the 13 nm sample. An analysis of
the polarized neutron data on both samples shows that in an individual MnO
nanoparticle about 80 of Mn ions order. These results can be explained by a
structure in which the monodisperse nanoparticles studied here have a core that
behaves similar to the bulk with a surface layer which does not contribute
significantly to the magnetic order.Comment: 7 pages, 5 figure
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