15,127 research outputs found
The effect of magnetic dipolar interactions on the interchain spin wave dispersion in CsNiF_3
Inelastic neutron scattering measurements were performed on the ferromagnetic
chain system CsNiF_3 in the collinear antiferromagnetic ordered state below T_N
= 2.67K. The measured spin wave dispersion was found to be in good agreement
with linear spin wave theory including dipolar interactions. The additional
dipole tensor in the Hamiltonian was essential to explain some striking
phenomena in the measured spin wave spectrum: a peculiar feature of the
dispersion relation is a jump at the zone center, caused by strong dipolar
interactions in this system. The interchain exchange coupling constant and the
planar anisotropy energy were determined within the present model to be J'/k_B
= -0.0247(12)K and A/k_B = 3.3(1)K. This gives a ratio J/J' \approx 500, using
the previously determined intrachain coupling constant J/k_B = 11.8$. The small
exchange energy J' is of the same order as the dipolar energy, which implies a
strong competition between the both interactions.Comment: 18 pages, TeX type, 7 Postscript figures included. To be published in
Phys. Rev.
Predicting Mercury's Precession using Simple Relativistic Newtonian Dynamics
We present a new simple relativistic model for planetary motion describing
accurately the anomalous precession of the perihelion of Mercury and its
origin. The model is based on transforming Newton's classical equation for
planetary motion from absolute to real spacetime influenced by the
gravitational potential and introducing the concept of influenced direction.Comment: 5 page
Predicting the relativistic periastron advance of a binary without curving spacetime
Relativistic Newtonian Dynamics, the simple model used previously for
predicting accurately the anomalous precession of Mercury, is now applied to
predict the periastron advance of a binary. The classical treatment of a binary
as a two-body problem is modified to account for the influence of the
gravitational potential on spacetime. Without curving spacetime, the model
predicts the identical equation for the relativistic periastron advance as the
post-Newtonian approximation of general relativity formalism thereby providing
further substantiation of this model.Comment: 6 pages, 2 figure
Isospin Asymmetry in Nuclei, Neutron Stars, and Heavy-Ion Collisions
The roles of isospin asymmetry in nuclei and neutron stars are investigated
using a range of potential and field-theoretical models of nucleonic matter.
The parameters of these models are fixed by fitting the properties of
homogeneous bulk matter and closed-shell nuclei. We discuss and unravel the
causes of correlations among the neutron skin thickness in heavy nuclei, the
pressure of beta-equilibrated matter at a density of 0.1 fm, and the
radii of moderate mass neutron stars. The influence of symmetry energy on
observables in heavy-ion collisions is summarized.Comment: 8 pages, 5 figures; Proceedings for the 21st Winter Workshop on
Nuclear Dynamics, Breckenridge, Colorado, February 5-12, 2005; To appear in
Heavy Ion Physic
Escape Orbits for Non-Compact Flat Billiards
It is proven that, under some conditions on , the non-compact flat
billiard
has no orbits going {\em directly} to . The relevance of such
sufficient conditions is discussed.Comment: 9 pages, LaTeX, 3 postscript figures available at
http://www.princeton.edu/~marco/papers/ . Minor changes since previously
posted version. Submitted to 'Chaos
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