78 research outputs found
Minimizing Effective Many-Body Interactions
A simple two-level model is developed and used to test the properties of
effective interactions for performing nuclear structure calculations in
truncated model spaces. It is shown that the effective many-body interactions
sensitively depend on the choice of the single-particle basis and they appear
to be minimized when a self- consistent Hartree-Fock basis is used.Comment: (15 pages of text and 1 postscript figure (Figure available upon
request), Preprint Number not assigned ye
Exact Solutions of Model Hamiltonian Problems with Effective Interactions
We demonstrate with soluble models how to employ the effective Hamiltonian
approach of Lee and Suzuki to obtain all the exact eigenvalues of the full
Hamiltonian. We propose a new iteration scheme to obtain the effective
Hamiltonian and demonstrate its convergence properties.Comment: 12 pages and 1 figur
Electron in a transverse harmonic cavity
We employ Hamiltonian light-front quantum field theory in a basis function
approach to solve the non-perturbative problem of an electron in a strong
scalar transverse confining potential. We evaluate both the invariant mass
spectra and the anomalous magnetic moment of the lowest state for this
two-scale system. The weak external field limit of the anomalous magnetic
moment agrees with the result of QED perturbation theory within the anticipated
accuracy.Comment: 4 pages, 3 figures, published versio
Auxiliary potential in no-core shell-model calculations
The Lee-Suzuki iteration method is used to include the folded diagrams in the
calculation of the two-body effective interaction between
two nucleons in a no-core model space. This effective interaction still depends
upon the choice of single-particle basis utilized in the shell-model
calculation. Using a harmonic-oscillator single-particle basis and the
Reid-soft-core {\it NN} potential, we find that overbinds
^4\mbox{He} in 0, 2, and model spaces. As the size of the
model space increases, the amount of overbinding decreases significantly. This
problem of overbinding in small model spaces is due to neglecting effective
three- and four-body forces. Contributions of effective many-body forces are
suppressed by using the Brueckner-Hartree-Fock single-particle Hamiltonian.Comment: 14 text pages and 4 figures (in postscript, available upon request).
AZ-PH-TH/94-2
Kinks in Discrete Light Cone Quantization
We investigate non-trivial topological structures in Discrete Light Cone
Quantization (DLCQ) through the example of the broken symmetry phase of the two
dimensional theory using anti periodic boundary condition (APBC). We
present evidence for degenerate ground states which is both a signature of
spontaneous symmetry breaking and mandatory for the existence of kinks. Guided
by a constrained variational calculation with a coherent state ansatz, we then
extract the vacuum energy and kink mass and compare with classical and semi -
classical results. We compare the DLCQ results for the number density of bosons
in the kink state and the Fourier transform of the form factor of the kink with
corresponding observables in the coherent variational kink state.Comment: 10 pages, 3 figure
Hamiltonian light-front field theory within an AdS/QCD basis
Non-perturbative Hamiltonian light-front quantum field theory presents
opportunities and challenges that bridge particle physics and nuclear physics.
Fundamental theories, such as Quantum Chromodynmamics (QCD) and Quantum
Electrodynamics (QED) offer the promise of great predictive power spanning
phenomena on all scales from the microscopic to cosmic scales, but new tools
that do not rely exclusively on perturbation theory are required to make
connection from one scale to the next. We outline recent theoretical and
computational progress to build these bridges and provide illustrative results
for nuclear structure and quantum field theory. As our framework we choose
light-front gauge and a basis function representation with two-dimensional
harmonic oscillator basis for transverse modes that corresponds with
eigensolutions of the soft-wall AdS/QCD model obtained from light-front
holography.Comment: To appear in the proceedings of Light-Cone 2009: Relativistic
Hadronic and Particle Physics, July 8-13, 2009, Sao Jose dos Campos, Brazi
Simple approximation for the starting-energy-independent two-body effective interaction with applications to 6Li
We apply the Lee-Suzuki iteration method to calculate the linked-folded
diagram series for a new Nijmegen local NN potential. We obtain an exact
starting-energy-independent effective two-body interaction for a multi-shell,
no-core, harmonic-oscillator model space. It is found that the resulting
effective-interaction matrix elements can be well approximated by the Brueckner
G-matrix elements evaluated at starting energies selected in a simple way.
These starting energies are closely related to the energies of the initial
two-particle states in the ladder diagrams. The ``exact'' and approximate
effective interactions are used to calculate the energy spectrum of 6Li in
order to test the utility of the approximate form.Comment: 15 text pages and 2 PostScript figures (available upon request).
University of Arizona preprint, Number unassigne
Novel NN interaction and the spectroscopy of light nuclei
Nucleon-nucleon (NN) phase shifts and the spectroscopy of nuclei
are successfully described by an inverse scattering potential that is separable
with oscillator form factors.Comment: 4 pages, 1 figure, 13 table
Perturbative S-matrix in discretized light cone quantization of two-dimensional \phi^4 theory
We study the S-matrix of two-dimensional \lambda\phi^4 theory in Discretized
Light Cone Quantization and show how the correct continuum limit is reached for
various processes in lowest order perturbation theory.Comment: title changed, clarifying statements adde
Hamiltonian Light-Front Field Theory: Recent Progress and Tantalizing Prospects
Fundamental theories, such as Quantum Electrodynamics (QED) and Quantum
Chromodynamics (QCD) promise great predictive power addressing phenomena over
vast scales from the microscopic to cosmic scales. However, new
non-perturbative tools are required for physics to span from one scale to the
next. I outline recent theoretical and computational progress to build these
bridges and provide illustrative results for Hamiltonian Light Front Field
Theory. One key area is our development of basis function approaches that cast
the theory as a Hamiltonian matrix problem while preserving a maximal set of
symmetries. Regulating the theory with an external field that can be removed to
obtain the continuum limit offers additional possibilities as seen in an
application to the anomalous magnetic moment of the electron. Recent progress
capitalizes on algorithm and computer developments for setting up and solving
very large sparse matrix eigenvalue problems. Matrices with dimensions of 20
billion basis states are now solved on leadership-class computers for their
low-lying eigenstates and eigenfunctions.Comment: 8 pages with 2 figure
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