374 research outputs found
Hypernuclei in the quark-meson coupling model
We present results of hypernuclei calculated in the latest quark-meson
coupling (QMC) model, where the effect of the mean scalar field in-medium on
the one-gluon exchange hyperfine interaction, is also included
self-consistently. The extra repulsion associated with this increased hyperfine
interaction in-medium completely changes the predictions for {\Sigma}
hypernuclei. Whereas in the earlier version of QMC they were bound by an amount
similar to {\Lambda} hypernuclei, they are unbound in the latest version of
QMC, in qualitative agreement with the experimental absence of such states.Comment: 6 pages, 3 figures, to be published in the proceedings of
Achievements and New Directions in Subatomic Physics: Workshop in Honour of
Tony Thomas' 60th Birthday, Adelaide, South Australia, 15-19 Feb 201
Quark structure and nuclear effective forces
We formulate the quark meson coupling model as a many-body effective
Hamiltonian. This leads naturally to the appearance of many-body forces. We
investigate the zero range limit of the model and compare its Hartree-Fock
Hamiltonian to that corresponding to the Skyrme effective force. By fixing the
three parameters of the model to reproduce the binding and symmetry energy of
nuclear matter, we find that it allows a very satisfactory interpretation of
the Skyrme force.Comment: 4 pages, 1tabl
Virtual Compton Scattering from the Proton and the Properties of Nucleon Excited States
We calculate the contributions to the generalized polarizabilities of
the proton in virtual Compton scattering. The following nucleon excitations are
included: , , , , ,
and . The relationship between nucleon
structure parameters, properties and the generalized polarizabilities of
the proton is illustrated.Comment: 13 pages of text (Latex) plus 4 figures (as uuencoded Z-compressed
.tar file created by csh script uufiles
Quarks in Finite Nuclei
We describe the development of a theoretical description of the structure of
finite nuclei based on a relativistic quark model of the structure of the bound
nucleons which interact through the (self-consistent) exchange of scalar and
vector mesons.Comment: Invited talks presented at the Joint Japan-Australian Workshop on
"Quarks, Hadrons and Nuclei", Adelaide, November 1995, to appear in
Australian Jounal of Physic
Finite Nuclei in the Quark-Meson Coupling (QMC) Model
We report the first use of the effective QMC energy density functional (EDF),
derived from a quark model of hadron structure, to study a broad range of
ground state properties of even-even nuclei across the periodic table in the
non-relativistic Hartree-Fock+BCS framework. The novelty of the QMC model is
that the nuclear medium effects are treated through modification of the
internal structure of the nucleon. The density dependence is microscopically
derived and the spin-orbit term arises naturally. The QMC EDF depends on a
single set of four adjustable parameters having clear physical basis. When
applied to diverse ground state data the QMC EDF already produces, in its
present simple form, overall agreement with experiment of a quality comparable
to a representative Skyrme EDF. There exist however multiple Skyrme paramater
sets, frequently tailored to describe selected nuclear phenomena. The QMC EDF
set of fewer parameters, as derived in this work, is not open to such
variation, chosen set being applied, without adjustment, to both the properties
of finite nuclei and nuclear matter.Comment: 9 pages, 1 table, 4 figures; in print in Phys. Rev. Letters. A minor
change in the abstract, a few typos corrected and some small technical
adjustments made to comply with the journal regulation
Lambda beta-decay in-medium
Abstract not availableP. A. M. Guichon, A. W. Thoma
Comment about pion electro-production and the axial form factors
The claim by Haberzettl (Phys.Rev.Lett.85 (2000) 3576) that the axial form
factor of the nucleon cannot be accessed through threshold pion
electroproduction is unfounded
New Predictions for generalized spin polarizabilities from heavy baryon chiral perturbation theory
We extract the next-to-next-to-leading order results for spin-flip
generalized polarizabilities (GPs) of the nucleon from the spin-dependent
amplitudes for virtual Compton scattering (VCS) at in heavy
baryon chiral perturbation theory. At this order, no unknown low energy
constants enter the theory, allowing us to make absolute predictions for all
spin-flip GPs. Furthermore, by using constraint equations between the GPs due
to nucleon crossing combined with charge conjugation symmetry of the VCS
amplitudes, we get a next-to-next-to-next-to-leading order prediction for one
of the GPs. We provide estimates for forthcoming double polarization
experiments which allow to access these spin-flip GPs of the nucleon.Comment: 15 pages, 3 figure
Binding of hypernuclei, and phtoproduction of -hypernuclei in the latest quark-meson coupling model
We study the binding of hypernuclei based on the latest version of
quark-meson coupling model, and estimate the phtoproduction cross sections for
the C()B reaction using the bound
spinors obtained in the model.Comment: 6 pages, 3 figures, Talk given at (Pre-symposium in) Sendai
International Symposium on Strangeness in Nuclear and Hadronic Systems
(SENDAI08), December (14)15-18, 2008, Tohoku Univ., Japa
- âŠ