206 research outputs found
Study of the ground-state energy of 40Ca with the CD-Bonn nucleon-nucleon potential
We have calculated the ground-state energy of the doubly-magic nucleus 40Ca
within the framework of the Goldstone expansion using the CD-Bonn
nucleon-nucleon potential. The short-range repulsion of this potential has been
renormalized by integrating out its high-momentum components so as to derive a
low-momentum potential V-low-k defined up to a cutoff momentum Lambda. A simple
criterion has been employed to establish a connection between this cutoff
momentum and the size of the two-nucleon model space in the harmonic oscillator
basis. This model-space truncation approach provides a reliable way to
renormalize the free nucleon-nucleon potential preserving its many-body
physics. The role of the 3p-3h and 4p-4h excitations in the description of the
ground state of 40Ca is discussed.Comment: 4 pages, 1 figure, 1 table, to be published in Physical Review
Reduced regulator dependence of neutron-matter predictions with chiral interactions
We calculate the energy per particle in infinite neutron matter
perturbatively using chiral N3LO two-body potentials plus N2LO three-body
forces. The cutoff dependence of the predictions is investigated by employing
chiral interactions with different regulators. We find that the inclusion of
three-nucleon forces, which are consistent with the applied two-nucleon
interaction, leads to a strongly reduced regulator dependence of the results.Comment: 7 pages, 8 figures, 1 table, to be published in Physical Review
The nuclear matter equation of state with consistent two- and three-body perturbative chiral interactions
We compute the energy per particle of infinite symmetric nuclear matter from
chiral N3LO (next-to-next-to-next-to-leading order) two-body potentials plus
N2LO three-body forces. The low-energy constants of the chiral three-nucleon
force that cannot be constrained by two-body observables are fitted to
reproduce the triton binding energy and the 3H-3He Gamow-Teller transition
matrix element. In this way, the saturation properties of nuclear matter are
reproduced in a parameter-free approach. The equation of state is computed up
to third order in many-body perturbation theory, with special emphasis on the
role of the third-order particle-hole diagram. The dependence of these results
on the cutoff scale and regulator function is studied. We find that the
inclusion of three-nucleon forces consistent with the applied two-nucleon
interaction leads to a reduced dependence on the choice of the regulator only
for lower values of the cutoff.Comment: 9 pages, 12 figures, 3 tables, to be published in Physical Review C.
arXiv admin note: text overlap with arXiv:1209.553
Chiral nucleon-nucleon forces in nuclear structure calculations
Realistic nuclear potentials, derived within chiral perturbation theory, are
a major breakthrough in modern nuclear structure theory, since they provide a
direct link between nuclear physics and its underlying theory, namely the QCD.
As a matter of fact, chiral potentials are tailored on the low-energy regime of
nuclear structure physics, and chiral perturbation theory provides on the same
footing two-nucleon forces as well as many-body ones. This feature fits well
with modern advances in ab-initio methods and realistic shell-model. Here, we
will review recent nuclear structure calculations, based on realistic chiral
potentials, for both finite nuclei and infinite nuclear matter.Comment: 10 pages, 8 figures, plenary talk presented at "Nucleus-Nucleus 2015"
Conference, 21-26 June 2015, Catania, to be published in the "Conference
Proceedings" Series of the Italian Physical Societ
Similarity of nuclear structure in 132Sn and 208Pb regions: proton-neutron multiplets
Starting from the striking similarity of proton-neutron multiplets in 134Sb
and 210Bi, we perform a shell-model study of nuclei with two additional protons
or neutrons to find out to what extent this analogy persists. We employ
effective interactions derived from the CD-Bonn nucleon-nucleon potential
renormalized by use of the V-low-k approach. The calculated results for 136Sb,
212Bi, 136I, and 212At are in very good agreement with the available
experimental data. The similarity between 132Sn and 208Pb regions is discussed
in connection with the effective interaction, emphasizing the role of core
polarization effects.Comment: 4 pages, 3 figures, 2 table
Realistic shell-model calculations for proton particle-neutron hole nuclei around 132Sn
We have performed shell-model calculations for nuclei with proton particles
and neutron holes around 132Sn using a realistic effective interaction derived
from the CD-Bonn nucleon-nucleon potential. For the proton-neutron channel this
is explicitly done in the particle-hole formalism. The calculated results are
compared with the available experimental data, particular attention being
focused on the proton particle-neutron hole multiplets. A very good agreement
is obtained for all the four nuclei considered, 132Sb, 130Sb, 133Te and 131Sb.
We predict many low-energy states which have no experimental counterpart. This
may stimulate, and be helpful to, future experiments.Comment: 8 pages, 6 figures, to be published on Physical Review
Study of nucleonic matter with a consistent two- and three-body perturbative chiral interaction
We calculate perturbatively the energy per nucleon in infinite nuclear matter
with a chiral N3LO (next-to-next-to-next-to-leading order) two-body potential
plus a N2LO three-body force (3BF). The 3BF low-energy constants which cannot
be constrained by two-body observables are chosen such as to reproduce the A=3
binding energies and the triton Gamow-Teller matrix element. This enables to
study the nuclear matter equation of state in a parameter-free approach.Comment: 7 pages, 5 figures, talk presented at "XIV Convegno su Problemi di
Fisica Nucleare Teorica", Cortona October 29-31, 2013. Submitted to Journal
of Physics: Conferences Serie
Nuclear Structure Calculations with Low-Momentum Potentials in a Model Space Truncation Approach
We have calculated the ground-state energy of the doubly magic nuclei 4He,
16O and 40Ca within the framework of the Goldstone expansion starting from
various modern nucleon-nucleon potentials. The short-range repulsion of these
potentials has been renormalized by constructing a low-momentum potential
V-low-k. We have studied the connection between the cutoff momemtum Lambda and
the size of the harmonic oscillator space employed in the calculations. We have
found a fast convergence of the results with a limited number of oscillator
quanta.Comment: 6 pages, 8 figures, to be published on Physical Review
Towards order-by-order calculations of the nuclear and neutron matter equations of state in chiral effective field theory
We calculate the nuclear and neutron matter equations of state from
microscopic nuclear forces at different orders in chiral effective field theory
and with varying momentum-space cutoff scales. We focus attention on how the
order-by-order convergence depends on the choice of resolution scale and the
implications for theoretical uncertainty estimates on the isospin asymmetry
energy. Specifically we study the equations of state using consistent NLO and
N2LO (next-to-next-to-leading order) chiral potentials where the low-energy
constants cD and cE associated with contact vertices in the N2LO chiral
three-nucleon force are fitted to reproduce the binding energies of 3H and 3He
as well as the beta-decay lifetime of 3H. At these low orders in the chiral
expansion there is little sign of convergence, while an exploratory study
employing the N3LO two-nucleon force together with the N2LO three-nucleon force
give first indications for (slow) convergence with low-cutoff potentials and
poor convergence with higher-cutoff potentials. The consistent NLO and N2LO
potentials described in the present work provide the basis for estimating
theoretical uncertainties associated with the order-by-order convergence of
nuclear many-body calculations in chiral effective field theory.Comment: 9 pages, 6 figures. Accepted for publication in Physical Review
Proton-Neutron Interaction near Closed Shells
Odd-odd nuclei around double shell closures are a direct source of
information on the proton-neutron interaction between valence nucleons. We have
performed shell-model calculations for doubly odd nuclei close to Pb,
Sn and Sn using realistic effective interactions derived from
the CD-Bonn nucleon-nucleon potential. The calculated results are compared with
the available experimental data, attention being focused on particle-hole and
particle-particle multiplets. While a good agreement is obtained for all the
nuclei considered, a detailed analysis of the matrix elements of the effective
interaction shows that a stronger core-polarization contribution seems to be
needed in the particle-particle case.Comment: 8 pages, 6 figures, Proccedings of the International Conference
"Nuclear Structure and Related Topics", Dubna, Russia, September 2-6, 2003,
to be published in Yadernaia Fizika (Physics of Atomic Nuclei
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