6,138 research outputs found
On Renyi entropies characterizing the shape and the extension of the phase space representation of quantum wave functions in disordered systems
We discuss some properties of the generalized entropies, called Renyi
entropies and their application to the case of continuous distributions. In
particular it is shown that these measures of complexity can be divergent,
however, their differences are free from these divergences thus enabling them
to be good candidates for the description of the extension and the shape of
continuous distributions. We apply this formalism to the projection of wave
functions onto the coherent state basis, i.e. to the Husimi representation. We
also show how the localization properties of the Husimi distribution on average
can be reconstructed from its marginal distributions that are calculated in
position and momentum space in the case when the phase space has no structure,
i.e. no classical limit can be defined. Numerical simulations on a one
dimensional disordered system corroborate our expectations.Comment: 8 pages with 2 embedded eps figures, RevTex4, AmsMath included,
submitted to PR
Quantum chaos in one dimension?
In this work we investigate the inverse of the celebrated
Bohigas-Giannoni-Schmit conjecture. Using two inversion methods we compute a
one-dimensional potential whose lowest N eigenvalues obey random matrix
statistics. Our numerical results indicate that in the asymptotic limit,
N->infinity, the solution is nowhere differentiable and most probably nowhere
continuous. Thus such a counterexample does not exist.Comment: 7 pages, 10 figures, minor correction, references extende
Spectral Properties of the Chalker-Coddington Network
We numerically investigate the spectral statistics of pseudo-energies for the
unitary network operator U of the Chalker--Coddington network. The shape of the
level spacing distribution as well the scaling of its moments is compared to
known results for quantum Hall systems. We also discuss the influence of
multifractality on the tail of the spacing distribution.Comment: JPSJ-style, 7 pages, 4 Postscript figures, to be published in J.
Phys. Soc. Jp
Fluctuation of the Correlation Dimension and the Inverse Participation Number at the Anderson Transition
The distribution of the correlation dimension in a power law band random
matrix model having critical, i.e. multifractal, eigenstates is numerically
investigated. It is shown that their probability distribution function has a
fixed point as the system size is varied exactly at a value obtained from the
scaling properties of the typical value of the inverse participation number.
Therefore the state-to-state fluctuation of the correlation dimension is
tightly linked to the scaling properties of the joint probability distribution
of the eigenstates.Comment: 4 pages, 5 figure
Global-Vector Representation of the Angular Motion of Few-Particle Systems II
The angular motion of a few-body system is described with global vectors
which depend on the positions of the particles. The previous study using a
single global vector is extended to make it possible to describe both natural
and unnatural parity states. Numerical examples include three- and four-nucleon
systems interacting via nucleon-nucleon potentials of AV8 type and a 3
system with a nonlocal potential. The results using the
explicitly correlated Gaussian basis with the global vectors are shown to be in
good agreement with those of other methods. A unique role of the unnatural
parity component, caused by the tensor force, is clarified in the state
of He. Two-particle correlation function is calculated in the coordinate
and momentum spaces to show different characteristics of the interactions
employed.Comment: 39 pages, 4 figure
Isospin Mass Splittings of Baryons in Potential Models
We discuss the isospin-breaking mass differences among baryons, with particular attention in the charm sector to the , models cannot accommodate the trend of the available data on charmed baryons. More precise measurements would offer the possibility of testing how well potential models describe the non-perturbative limit of QCD
Second bound state of the positronium molecule and biexcitons
A new, hitherto unknown bound state of the positronium molecule, with orbital
angular momentum L=1 and negative parity is reported. This state is stable
against autodissociation even if the masses of the positive and negative
charges are not equal. The existence of a similar state in two-dimension has
also been investigated. The fact that the biexcitons have a second bound state
may help the better understanding of their binding mechanism.Comment: Latex, 8 pages, 2 Postscript figure
Baryons Electromagnetic Mass Splittings in Potential Models
We study electromagnetic mass splittings of charmed baryons. We point out
discrepancies among theoretical predictions in non-relativistic potential
models. None of them seems supported by experimental data. A new calculation is
presented.Comment: 4 pages, Proc. of ISS97 Tashkent 6-13 Oct. 9
Isospin Splittings of Baryons
We discuss the isospin-breaking mass differences among baryons, with
particular attention in the charm sector to the ,
, and splittings. Simple potential
models cannot accommodate the trend of the available data on charm baryons.
More precise measurements would offer the possibility of testing how well
potential models describe the non-perturbative limit of QCD.Comment: 4 pages, aipproc.sty, Proceeding of Hadron 9
Generic spectral properties of right triangle billiards
This article presents a new method to calculate eigenvalues of right triangle
billiards. Its efficiency is comparable to the boundary integral method and
more recently developed variants. Its simplicity and explicitness however allow
new insight into the statistical properties of the spectra. We analyse
numerically the correlations in level sequences at high level numbers (>10^5)
for several examples of right triangle billiards. We find that the strength of
the correlations is closely related to the genus of the invariant surface of
the classical billiard flow. Surprisingly, the genus plays and important role
on the quantum level also. Based on this observation a mechanism is discussed,
which may explain the particular quantum-classical correspondence in right
triangle billiards. Though this class of systems is rather small, it contains
examples for integrable, pseudo integrable, and non integrable (ergodic,
mixing) dynamics, so that the results might be relevant in a more general
context.Comment: 18 pages, 8 eps-figures, revised: stylistic changes, improved
presentatio
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