2,729 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
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
The Nambu-Jona-Lasinio Chiral Soliton with Constrained Baryon Number
A regularization for the baryon number consistent with the energy in the
Nambu-Jona-Lasinio model is introduced. The soliton solution is constructed
with the regularized baryon number constrained to unity. It is furthermore
demonstrated that this constraint prevents the soliton from collapsing when
scalar fields are allowed to be space dependent. In this scheme the scalar
fields actually vanish at the origin reflecting a partial restoration of chiral
symmetry. Also the influence of this constraint on some static properties of
baryons is discussed.Comment: 10 LaTeX pages 4 figures, report no UNITU-THEP-7/199
Nucleon Structure Functions from a Chiral Soliton in the Infinite Momentum Frame
We study the frame dependence of nucleon structure functions obtained within
a chiral soliton model for the nucleon. Employing light cone coordinates and
introducing collective coordinates together with their conjugate momenta,
translational invariance of the solitonic quark fields (which describe the
nucleon as a localized object) is restored. This formulation allows us to
perform a Lorentz boost to the infinite momentum frame of the nucleon. The
major result is that the Lorentz contraction associated with this boost causes
the leading twist contribution to the structure functions to properly vanish
when the Bjorken variable exceeds unity. Furthermore we demonstrate that
for structure functions calculated in the valence quark approximation to the
Nambu--Jona--Lasinio chiral soliton model the Lorentz contraction also has
significant effects on the structure functions for moderate values of the
Bjorken variable .Comment: 16 pages, 1 figure, revised version to be published in Int. J. Mod.
Phys.
- …