912 research outputs found
Phonon density of states and compression behavior in iron sulfide under pressure
We report the partial phonon densities of states (DOS) of iron sulfide, a possible component of the rocky planet's core, measured by the Fe-57 nuclear resonant inelastic x-ray scattering and calculate the total phonon DOS under pressure. From the phonon DOS, we drive thermodynamic parameters. A comparison of the observed and estimated compressibilities makes it clear that there is a large pure electronic contribution in the observed compressibility in the metallic state. Our results present the observation of thermodynamic parameters of iron sulfide with the low-spin state of an Fe2+ ion at the high density, which is similar to the condition of the Martian core
H-Dihyperon in Quark Cluster Model
The H dihyperon (DH) is studied in the framework of the SU(3) chiral quark
model. It is shown that except the chiral field, the overall effect of
the other SU(3) chiral fields is destructive in forming a stable DH. The
resultant mass of DH in a three coupled channel calculation is ranged from 2225
to 2234 .Comment: 9 pages, emte
Gauge transformations and symmetries of integrable systems
We analyze several integrable systems in zero-curvature form within the
framework of invariant gauge theory. In the Drienfeld-Sokolov gauge
we derive a two-parameter family of nonlinear evolution equations which as
special cases include the Kortweg-de Vries (KdV) and Harry Dym equations. We
find residual gauge transformations which lead to infinintesimal symmetries of
this family of equations. For KdV and Harry Dym equations we find an infinite
hierarchy of such symmetry transformations, and we investigate their relation
with local conservation laws, constants of the motion and the bi-Hamiltonian
structure of the equations. Applying successive gauge transformatinos of Miura
type we obtain a sequence of gauge equivalent integrable systems, among them
the modified KdV and Calogero KdV equations.Comment: 18pages, no figure Journal versio
Dynamics of (SUSY) AdS Space Isometry Breaking
Actions governing the dynamics of the Nambu-Goldstone modes resulting from
the spontaneous breaking of the SO(4,2) and isometries of five
dimensional anti-de Sitter space () and SUSY
spaces respectively due to a restriction of the motion to embedded four
dimensional space and four dimensional Minkowski space () probe
branes are presented. The dilatonic Nambu-Goldstone mode governing the motion
of the space probe brane into the covolume of the SUSY
space is found to be unstable. No such instablility appears in the other cases.
Gauging these symmetries leads to an Einstein-Hilbert action containing, in
addition to the gravitational vierbein, a massive Abelian vector field coupled
to gravity.Comment: 6 pages, 0 figures, to appear in Proceedings of IRGAC 2006: 2nd
International Conference on Quantum Theories and Renormalization Group in
Gravity and Cosmology, Barcelon
Benchmark Test Calculation of a Four-Nucleon Bound State
In the past, several efficient methods have been developed to solve the
Schroedinger equation for four-nucleon bound states accurately. These are the
Faddeev-Yakubovsky, the coupled-rearrangement-channel Gaussian-basis
variational, the stochastic variational, the hyperspherical variational, the
Green's function Monte Carlo, the no-core shell model and the effective
interaction hyperspherical harmonic methods. In this article we compare the
energy eigenvalue results and some wave function properties using the realistic
AV8' NN interaction. The results of all schemes agree very well showing the
high accuracy of our present ability to calculate the four-nucleon bound state.Comment: 17 pages, 1 figure
Tests of Transfer Reaction Determinations of Astrophysical S-Factors
The reaction has been used to determine
asymptotic normalization coefficients for transitions to the ground and first
excited states of . The coefficients provide the normalization for
the tails of the overlap functions for and allow us
to calculate the S-factors for at astrophysical
energies. The calculated S-factors are compared to measurements and found to be
in very good agreement. This provides the first test of this indirect method to
determine astrophysical direct capture rates using transfer reactions. In
addition, our results yield S(0) for capture to the ground and first excited
states in , without the uncertainty associated with extrapolation from
higher energies.Comment: 6 pages, 2 figure
Nano-displacement measurements using spatially multimode squeezed light
We demonstrate the possibility of surpassing the quantum noise limit for
simultaneous multi-axis spatial displacement measurements that have zero mean
values. The requisite resources for these measurements are squeezed light beams
with exotic transverse mode profiles. We show that, in principle, lossless
combination of these modes can be achieved using the non-degenerate Gouy phase
shift of optical resonators. When the combined squeezed beams are measured with
quadrant detectors, we experimentally demonstrate a simultaneous reduction in
the transverse x- and y- displacement fluctuations of 2.2 dB and 3.1 dB below
the quantum noise limit.Comment: 21 pages, 9 figures, submitted to "Special Issue on Fluctuations &
Noise in Photonics & Quantum Optics" of J. Opt.
Precise solution of few-body problems with stochastic variational method on correlated Gaussian basis
Precise variational solutions are given for problems involving diverse
fermionic and bosonic -body systems. The trial wave functions are chosen
to be combinations of correlated Gaussians, which are constructed from products
of the single-particle Gaussian wave packets through an integral
transformation, thereby facilitating fully analytical calculations of the
matrix elements. The nonlinear parameters of the trial function are chosen by a
stochastic technique. The method has proved very efficient, virtually exact,
and it seems feasible for any few-body bound-state problems emerging in nuclear
or atomic physics.Comment: 39 pages (revtex) + 3 figures (appended as compressed uuencoded .ps
files
Low-lying continuum structures in B8 and Li8 in a microscopic model
We search for low-lying resonances in the B8 and Li8 nuclei using a
microscopic cluster model and a variational scattering method, which is
analytically continued to complex energies. After fine-tuning the
nucleon-nucleon interaction to get the known 1+ state of B8 at the right
energy, we reproduce the known spectra of the studied nuclei. In addition, our
model predicts a 1+ state at 1.3 MeV in B8, relative to the Be7+p threshold,
whose corresponding pair is situated right at the Li7+n threshold in Li8.
Lacking any experimental evidence for the existence of such states, it is
presently uncertain whether these structures really exist or they are spurious
resonances in our model. We demonstrate that the predicted state in B8, if it
exists, would have important consequences for the understanding of the
astrophysically important Be7(p,gamma)B8 reaction.Comment: 6 pages with 1 figure. The postscript file and more information are
available at http://nova.elte.hu/~csot
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