3,136 research outputs found
Benchmarks of the full configuration interaction, Monte Carlo shell model, and no-core full configuration methods
We report no-core solutions for properties of light nuclei with three
different approaches in order to assess the accuracy and convergence rates of
each method. Full configuration interaction (FCI), Monte Carlo shell model
(MCSM) and no core full configuration (NCFC) approaches are solved separately
for the ground state energy and other properties of seven light nuclei using
the realistic JISP16 nucleon-nucleon interaction. The results are consistent
among the different approaches. The methods differ significantly in how the
required computational resources scale with increasing particle number for a
given accuracy.Comment: 19 pages, 14 figures, 6 table
Nucleon-Nucleon Scattering in a Harmonic Potential
The discrete energy-eigenvalues of two nucleons interacting with a
finite-range nuclear force and confined to a harmonic potential are used to
numerically reconstruct the free-space scattering phase shifts. The extracted
phase shifts are compared to those obtained from the exact continuum scattering
solution and agree within the uncertainties of the calculations. Our results
suggest that it might be possible to determine the amplitudes for the
scattering of complex systems, such as n-d, n-t or n-alpha, from the
energy-eigenvalues confined to finite volumes using ab-initio bound-state
techniques.Comment: 19 pages, 13 figure
Local three-nucleon interaction from chiral effective field theory
The three-nucleon (NNN) interaction derived within the chiral effective field
theory at the next-to-next-to-leading order (N2LO) is regulated with a function
depending on the magnitude of the momentum transfer. The regulated NNN
interaction is then local in the coordinate space, which is advantages for some
many-body techniques. Matrix elements of the local chiral NNN interaction are
evaluated in a three-nucleon basis. Using the ab initio no-core shell model
(NCSM) the NNN matrix elements are employed in 3H and 4He bound-state
calculations.Comment: 17 pages, 9 figure
The structure of the QED-Vacuum and Electron-Positron Pair Production in Super-Intense, pulsed Laser Fields
We discuss electron-positron pair-production by super-intense, short laser
pulses off the physical vacuum state locally deformed by (stripped) nuclei with
large nuclear charges. Consequences of non-perturbative vacuum polarisation
resulting from such a deformation are shortly broached. Production
probabilities per pulse are calculated.Comment: 10 pages, 1 figure, submitted to Journal of Physics
Factorization of shell-model ground-states
We present a new method that accurately approximates the shell-model
ground-state by products of suitable states. The optimal factors are determined
by a variational principle and result from the solution of rather
low-dimensional eigenvalue problems. The power of this method is demonstrated
by computations of ground-states and low-lying excitations in sd-shell and
pf-shell nuclei.Comment: 5+epsilon pages, 5 eps-figures. Main additions: wave-function
overlaps, angular momentum expectation values, application to Ni56. To be
published as Rapid Communication in PR
Coherent carrier dynamics in semiconductor superlattices
We investigate the coherent dynamics of carriers in semiconductor
superlattices driven by ac-dc electric fields. We solve numerically the
time-dependent effective-mass equation for the envelope function. We find that
carriers undergo Rabi oscillations when the driving frequency is close to the
separation between minibands.Comment: REVTEX (6 pages) and 3 figures (PostScript). Accepted in Physics
Letters
Yukawa model on a lattice: two body states
We present first results of the solutions of the Yukawa model as a Quantum
Field Theory (QFT) solved non perturbatively with the help of lattice
calculations. In particular we will focus on the possibility of binding two
nucleons in the QFT, compared to the non relativistic result.Comment: 3 pages, talk at "IVth International Conference on Quarks and Nuclear
Physics" (Madrid, June 2006
Resonant Photon-Assisted Tunneling Through a Double Quantum Dot: An Electron Pump From Spatial Rabi Oscillations
The time average of the fully nonlinear current through a double quantum dot,
subject to an arbitrary combination of ac and dc voltages, is calculated
exactly using the Keldysh nonequilibrium Green function technique. When driven
on resonance, the system functions as an efficient electron pump due to Rabi
oscillation between the dots. The pumping current is maximum when the coupling
to the leads equals the Rabi frequency.Comment: 6 pages, REVTEX 3.0, 3 postscript figure
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