505 research outputs found
Pion correlation from Skyrmion-AntiSkyrmion annihilation
We study two pion correlations from Skyrmion and antiSkyrmion collision,
using the product ansatz and an approximate random grooming method for nucleon
projection. The spatial-isospin coupling inherent in the Skyrme model, along
with empirical averages, leads to correlations not only among pions of like
charges but also among unlike charge types.Comment: uuencoded files of REVTeX and postscript, 18 pages including 2
figures, submitted to Phys.Rev.
Pion-delta sigma-term
We use a configuration space chiral model in order to evaluate nucleon and
delta sigma-terms. Analytic expressions are consistent with chiral counting
rules and give rise to expected non-analytic terms in the chiral limit. We
obtain the results MeV and MeV, which are
very close to values extracted from experiment and produced by other groups.Comment: 18 pages, 4 figure
The nucleus as a fluid of skyrmions: Energy levels and nucleon properties in the medium
A model of a fluid of skyrmions coupled to a scalar and to the \o meson
mean fields is developed. The central and spin-orbit potentials of a skyrmion
generated by the fields predict correct energy levels in selected closed shell
nuclei. The effect of the meson fields on the properties of skyrmions in nuclei
is investigated.Comment: Latex format, 6 figures, Journal of Physics G, to be publishe
High-density Skyrmion matter and Neutron Stars
We examine neutron star properties based on a model of dense matter composed
of B=1 skyrmions immersed in a mesonic mean field background. The model
realizes spontaneous chiral symmetry breaking non-linearly and incorporates
scale-breaking of QCD through a dilaton VEV that also affects the mean fields.
Quartic self-interactions among the vector mesons are introduced on grounds of
naturalness in the corresponding effective field theory. Within a plausible
range of the quartic couplings, the model generates neutron star masses and
radii that are consistent with a preponderance of observational constraints,
including recent ones that point to the existence of relatively massive neutron
stars with mass M 1.7 Msun and radius R (12-14) km. If the existence of neutron
stars with such dimensions is confirmed, matter at supra-nuclear density is
stiffer than extrapolations of most microscopic models suggest.Comment: 27 pages, 5 figures, AASTeX style; to be published in The
Astrophysical Journa
Topology in Physics - A Perspective
This article, written in honor of Fritz Rohrlich, briefly surveys the role of
topology in physics.Comment: 16pp, 2 figures included (encapsulated postscript
The Breathing Modes of the Skyrmion and the Spin-Orbit Interaction
The coupling of the breathing and rotational modes of the skyrmion-skyrmion
system leads to a nucleon-nucleon spin-orbit interaction of short range, as
well as to spin-orbit potentials for the transitions , and . The longest range behaviour of these
spin-orbit potentials is calculated in closed form.Comment: Latex, figures not include
The Skyrmion strikes back: baryons and a new large limit
In the large limit of QCD, baryons can be modeled as solitons, for
instance, as Skyrmions. This modeling has been justified by Witten's
demonstration that all properties of baryons and mesons scale with
in the same way as the analogous meson-based soliton model scales with a
generic meson-meson coupling constant . An alternative large limit
(the orientifold large limit) has recently been proposed in which quarks
transform in the two-index antisymmetric representation of . By
carrying out the analog of Witten's analysis for the new orientifold large
limit, we show that baryons and solitons can also be identified in the
orientifold large limit. However, in the orientifold large limit,
the interaction amplitudes and matrix elements scale with in the
same way as soliton models scale with the generic meson coupling constant
rather than as as in the traditional large limit.Comment: 10 pages, 26 figure
Pion-Nucleon Scattering Relations at Next-to-Leading Order in 1/N_c
We obtain relations between partial-wave amplitudes for pi-N-->pi-N and
pi-N-->pi-Delta directly from large N_c QCD. While linear relations among
certain amplitudes holding at leading order (LO) in 1/N_c were derived in the
context of chiral soliton models two decades ago, the present work employs a
fully model-independent framework based on consistency with the large N_c
expansion. At LO we reproduce the soliton model results; however, this method
allows for systematic corrections. At next-to-leading order (NLO), most
relations require additional unknown functions beyond those appearing at
leading order (LO) and thus have little additional predictive power. However,
three NLO relations for the pi-N-->pi-Delta reaction are independent of unknown
functions and make predictions accurate at this order. The amplitudes relevant
to two of these relations were previously extracted from experiment. These
relations describe experiment dramatically better than their LO counterparts.Comment: 8 pages, 2 figures; references adde
Solitons and Black Holes in a Generalized Skyrme Model with Dilaton-Quarkonium field
Skyrme theory is among the viable effective theories which emerge from
low-energy limit of quantum chromodynamics. Many of its generalizations include
also a dilaton. Here we find new self-gravitating solutions, both solitons and
black holes, in a Generalized Skyrme Model (GSM) in which a dilaton is present.
The investigation of the properties of the solutions is done numerically. We
find that the introduction of the dilaton in the theory does not change the
picture qualitatively, only quantitatively. The model considered here has one
free parameter more than the Einstein-Skyrme model which comes from the
potential of the dilaton. We have applied also the turning point method to
establish that one of the black-hole branches of solutions is unstable. The
turning point method here is based on the first law of black-hole
thermodynamics a detailed derivation of which is given in the Appendix of the
paper.Comment: 19 pages, 10 figures; v2: typos corrected, comments adde
Structure of solutions of the Skyrme model on three-sphere. Numerical results
The hedgehog Skyrme model on three-sphere admits very rich spectrum of
solitonic solutions which can be encompassed by a strikingly simple scheme. The
main result of this paper is the statement of the tripartite structure of
solutions of the model and the discovery in what configurations these solutions
appear. The model contains features of more complicated models in General
Relativity and as such can give insight into them.Comment: 20 pages, 13 figures in, with emai
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