4,614 research outputs found
The Skyrme Model for Baryons
We review the Skyrme model approach which treats baryons as solitons of an
effective meson theory. We start out with a historical introduction and a
concise discussion of the original two flavor Skyrme model and its
interpretation. Then we develop the theme, motivated by the large
approximation of QCD, that the {\it effective} Lagrangian of QCD is in fact one
which contains just mesons of all spins. When this Lagrangian is (at least
approximately) determined from the meson sector it should then yield a zero
parameter description of the baryons. We next discuss the concept of chiral
symmetry and the technology involved in handling the three flavor extension of
the model at the collective level. This material is used to discuss properties
of the light baryons based on three flavor meson Lagrangians containing just
pseudoscalars and also pseudoscalars plus vectors. The improvements obtained by
including vectors are exemplified in the treatment of the {\it proton spin
puzzle}.Comment: Invited review for INSA-Book-2000 38 pages, 4 figures included via
epsfi
Particle Conjugation and the Corrections to
We impose the requirement that the isovector axial vector current for the
soliton sector of the chiral quark model transforms correctly under particle
conjugation. This forces us to choose an otherwise arbitrary ordering of
collective space operators in such a way that the next--to--leading
correction to vanishes.Comment: 6 pages LaTeX, SU--4240--588, UNITU--THEP--23/199
Heavy Baryons with Strangeness in a Soliton Model
We present results from a chiral soliton model calculation for the spectrum
of baryons with a single heavy quark (charm or bottom) and non-zero
strangeness. We treat the strange components within a three flavor collective
coordinate quantization of the soliton that fully accounts for light flavor
symmetry breaking. Heavy baryons emerge by binding a heavy meson to the
soliton. The dynamics of this heavy meson is described by the heavy quark
effective theory with finite mass effects included.Comment: Ten pages, one figures, two tables, version to be published in PL
Spin and chiral stiffness of the XY spin glass in two dimensions
We analyze the zero-temperature behavior of the XY Edwards-Anderson spin
glass model on a square lattice. A newly developed algorithm combining exact
ground-state computations for Ising variables embedded into the planar spins
with a specially tailored evolutionary method, resulting in the genetic
embedded matching (GEM) approach, allows for the computation of numerically
exact ground states for relatively large systems. This enables a thorough
re-investigation of the long-standing questions of (i) extensive degeneracy of
the ground state and (ii) a possible decoupling of spin and chiral degrees of
freedom in such systems. The new algorithm together with appropriate choices
for the considered sets of boundary conditions and finite-size scaling
techniques allows for a consistent determination of the spin and chiral
stiffness scaling exponents.Comment: 6 pages, 2 figures, proceedings of the HFM2006 conference, to appear
in a special issue of J. Phys.: Condens. Matte
Scaling Behavior in Soliton Models
In the framework of chiral soliton models we study the behavior of static
nucleon properties under rescaling of the parameters describing the effective
meson theory. In particular we investigate the question of whether the
Brown--Rho scaling laws are general features of such models. When going beyond
the simple Skyrme model we find that restrictive constraints need to be imposed
on the mesonic parameters in order to maintain these scaling laws. Furthermore,
in the case when vector mesons are included in the model it turns out that the
isoscalar form factor no longer scales according to these laws. Finally we note
that, in addition to the exact scaling laws of the model, one may construct
approximate {\it local scaling laws}, which depend of the particular choice of
Lagrangian parameters.Comment: 10 pages Latex, figures added using epsfi
Autoplot: A browser for scientific data on the web
Autoplot is software developed for the Virtual Observatories in Heliophysics
to provide intelligent and automated plotting capabilities for many typical
data products that are stored in a variety of file formats or databases.
Autoplot has proven to be a flexible tool for exploring, accessing, and viewing
data resources as typically found on the web, usually in the form of a
directory containing data files with multiple parameters contained in each
file. Data from a data source is abstracted into a common internal data model
called QDataSet. Autoplot is built from individually useful components, and can
be extended and reused to create specialized data handling and analysis
applications and is being used in a variety of science visualization and
analysis applications. Although originally developed for viewing
heliophysics-related time series and spectrograms, its flexible and generic
data representation model makes it potentially useful for the Earth sciences.Comment: 16 page
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