382 research outputs found
Ab initio optical potentials and nucleon scattering on medium mass nuclei
We show the first results for the elastic scattering of neutrons off oxygen
and calcium isotopes obtained from ab initio optical potentials. The potential
is derived using self consistent Green's function theory (SCGF) with the
saturating chiral interaction NNLO. Our calculations are
compared to available scattering data and show that it is possible to reproduce
low energy scattering observables in medium mass nuclei from first principles.Comment: 6 pages, 4 figures, Zakopane conference on nuclear physic
Chiral three-nucleon forces and the evolution of correlations along the oxygen isotopic chain
The impact of three-nucleon forces (3NFs) along the oxygen chain is
investigated for the spectral distribution for attachment and removal of a
nucleon, spectroscopic factors and matter radii. We employ self-consistent
Green's function (SCGF) theory which allows a comprehensive calculation of the
single particle spectral function. For the closed subshell isotopes, O,
O, O, O and O, we perform calculations with the
Dyson-ADC(3) method. The remaining open shell isotopes are studied using the
newly developed Gorkov-SCGF formalism up to second order. We produce plots for
the full-fledged spectral distributions. The spectroscopic factors for the
dominant quasiparticle peaks are found to depend very little on the leading
order (NNLO) chiral 3NFs. The latters have small impact on the calculated
matter radii, which, however are consistently obtained smaller than experiment.
Similarly, single particle spectra tend to be diluted with respect to
experiment. This effect might hinder, to some extent, the onset of correlations
and screen the quenching of calculated spectroscopic factors. The most
important effects of 3NFs is thus the fine tuning of the energies for the
dominant quasiparticle states, which govern the shell evolution and the
position of driplines. Although present chiral NNLO 3NFs interactions do
reproduce the binding energies correctly in this mass region, the details of
the nuclear wave function remain at odd with the experiment showing too small
radii and a too dilute single particle spectrum, similar to what already
pointed out for larger masses. This suggests a lack of repulsion in the present
model of NN+3N interactions which is mildly apparent already for masses in the
A=14--28 range.Comment: 13 pages, accepted for publication on Phys. Rev.
Structure of A = 7 - 8 nuclei with two- plus three-nucleon interactions from chiral effective field theory
We solve the ab initio no-core shell model (NCSM) in the complete Nmax = 8
basis for A = 7 and A = 8 nuclei with two-nucleon and three-nucleon
interactions derived within chiral effective field theory (EFT). We find that
including the chiral EFT three-nucleon interaction in the Hamiltonian improves
overall good agreement with experimental binding energies, excitation spectra,
transitions and electromagnetic moments. We predict states that exhibit
sensitivity to including the chiral EFT three-nucleon interaction but are not
yet known experimentally.Comment: 10 pages, 6 figures, updated references and corrected a typ
Boson-fermion mapping and dynamical supersymmetry in fermion models
We show that a dynamical supersymmetry can appear in a purely fermionic
system. This ``supersymmetry without bosons" is constructed by application of a
recently introduced boson-fermion Dyson mapping from a fermion space to a space
comprised of collective bosons and ideal fermions. In some algebraic fermion
models of nuclear structure, particular Hamiltonians may lead to collective
spectra of even and odd nuclei that can be unified using the dynamical
supersymmetry concept with Pauli correlations exactly taken into account.Comment: 20 pages. Revtex. One PostScript figure available on request from P
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
From non-Hermitian effective operators to large-scale no-core shell model calculations for light nuclei
No-core shell model (NCSM) calculations using ab initio effective
interactions are very successful in reproducing experimental nuclear spectra.
The main theoretical approach is the use of effective operators, which include
correlations left out by the truncation of the model space to a numerically
tractable size. We review recent applications of the effective operator
approach, within a NCSM framework, to the renormalization of the
nucleon-nucleon interaction, as well as scalar and tensor operators.Comment: To be submited to J. Phys. A, special issue on "The Physics of
Non-Hermitian Operators
Proton radii of 4,6,8He isotopes from high-precision nucleon-nucleon interactions
Recently, precision laser spectroscopy on 6He atoms determined accurately the
isotope shift between 4He and 6He and, consequently, the charge radius of 6He.
A similar experiment for 8He is under way. We have performed large-scale ab
initio calculations for 4,6,8He isotopes using high-precision nucleon-nucleon
(NN) interactions within the no-core shell model (NCSM) approach. With the
CD-Bonn 2000 NN potential we found point-proton root-mean-square (rms) radii of
4He and 6He 1.45(1) fm and 1.89(4), respectively, in agreement with experiment
and predict the 8He point proton rms radius to be 1.88(6) fm. At the same time,
our calculations show that the recently developed nonlocal INOY NN potential
gives binding energies closer to experiment, but underestimates the charge
radii.Comment: 5 pages, 9 figure
No-Core Shell Model for Nuclear Systems with Strangeness
We report on a novel ab initio approach for nuclear few- and many-body
systems with strangeness. Recently, we developed a relevant no-core shell model
technique which we successfully applied in first calculations of lightest
hypernuclei. The use of a translationally invariant finite harmonic
oscillator basis allows us to employ large model spaces, compared to
traditional shell model calculations, and use realistic nucleon-nucleon and
nucleon-hyperon interactions (such as those derived from EFT). We discuss
formal aspects of the methodology, show first demonstrative results for
H, H and He, and give outlook.Comment: 4 pages, 3 figures; Proceedings of the 22nd European Conference on
Few Body Problems in Physics, 9 - 13 September, 2013, Cracow, Polan
Properties of C in the {\it ab initio} nuclear shell-model
We obtain properties of C in the {\it ab initio} no-core nuclear
shell-model. The effective Hamiltonians are derived microscopically from the
realistic CD-Bonn and the Argonne V8' nucleon-nucleon (NN) potentials as a
function of the finite harmonic oscillator basis space. Binding energies,
excitation spectra and electromagnetic properties are presented for model
spaces up to . The favorable comparison with available data is a
consequence of the underlying NN interaction rather than a phenomenological
fit.Comment: 9 pages, 2 figure
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