333 research outputs found
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
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
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
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
How to reconcile the Rosenbluth and the polarization transfer method in the measurement of the proton form factors
The apparent discrepancy between the Rosenbluth and the polarization transfer
method for the ratio of the electric to magnetic proton form factors can be
explained by a two-photon exchange correction which does not destroy the
linearity of the Rosenbluth plot. Though intrinsically small, of the order of a
few percent of the cross section, this correction is kinematically enhanced in
the Rosenbluth method while it is small for the polarization transfer method,
at least in the range of (Q^2) where it has been used until now.Comment: 4 pages, 4 figures. Version accepted for publication in Phys. Rev.
Let
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
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
Physical Origin of Density Dependent Force of the Skyrme Type within the Quark Meson Coupling Model
A density dependent, effective nucleon-nucleon force of the Skyrme type is
derived from the quark-meson coupling model -- a self-consistent, relativistic
quark level description of nuclear matter. This new formulation requires no
assumption that the mean scalar field is small and hence constitutes a
significant advance over earlier work. The similarity of the effective
interaction to the widely used SkM force encourages us to apply it to a
wide range of nuclear problems, beginning with the binding energies and charge
distributions of doubly magic nuclei. Finding acceptable results in this
conventional arena, we apply the same effective interaction, within the
Hartree-Fock-Bogoliubov approach, to the properties of nuclei far from
stability. The resulting two neutron drip lines and shell quenching are quite
satisfactory. Finally, we apply the relativistic formulation to the properties
of dense nuclear matter in anticipation of future application to the properties
of neutron stars.Comment: 2 references added, some changes in the tex
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
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