55 research outputs found
Density functional for pairing with particle number conservation
In this work, a new functional is introduced to treat pairing correlations in
finite many-body systems. Guided by the projected BCS framework, the energy is
written as a functional of occupation numbers. It is shown to generalize the
BCS approach and to provide an alternative to Variation After Projection
framework. Illustrations of the new approach are given for the pairing
Hamiltonian for various particle numbers and coupling strengths. In all case, a
very good agreement with the exact solution is found.Comment: Proceeding of the International Symposium: Forefronts of Researches
in Exotic Nuclear Structures- Niigata201
Beyond mean-field calculation for pairing correlation
The recently proposed Symmetry-Conserving Energy Density Functional approach
[G. Hupin, D. Lacroix and M. Bender, Phys. Rev. C84, 014309 (2011)] is applied
to perform Variation After Projection onto good particle number using Skyrme
interaction, including density dependent terms. We present a systematic study
of the Kr and Sn isotopic chains. This approach leads to non-zero pairing in
magic nuclei and a global enhancement of the pairing gap compared to the
original theory that breaks the particle number symmetry. The need to
consistently readjust the pairing effective interaction strength is discussed.Comment: 7 pages, 9 figure
On the formulation of functional theory for pairing with particle number restoration
The restoration of particle number within Energy Density Functional theory is
analyzed. It is shown that the standard method based on configuration mixing
leads to a functional of both the projected and non-projected densities. As an
alternative that might be advantageous for mass models, nuclear dynamics and
thermodynamics, we propose to formulate the functional in terms directly of the
one-body and two-body density matrices of the state with good particle number.
Our approach does not contain the pathologies recently observed when restoring
the particle number in an Energy Density Functional framework based on
transition density matrices and can eventually be applied with functionals
having arbitrary density dependencies.Comment: 11 pages, 3 figure
Advances in the ab initio description of nuclear three-cluster systems
We introduce the extension of the ab initio no-core shell model with
continuum to describe three-body cluster systems. We present results for the
ground state of 6He and show improvements with respect to the description
obtained within the no-core shell model and the no-core shell model/resonating
group methods.Comment: Proceedings of the 21st International Conference on Few-Body Problems
in Physics. May 18-22, 2015. Chicago, Illinois, US
How many-body correlations and -clustering shape He
The Borromean He nucleus is an exotic system characterized by two `halo'
neutrons orbiting around a compact He (or ) core, in which the
binary subsystems are unbound. The simultaneous reproduction of its small
binding energy and extended matter and point-proton radii has been a challenge
for {\em ab initio} theoretical calculations based on traditional bound-state
methods. Using soft nucleon-nucleon interactions based on chiral effective
field theory potentials, we show that supplementing the model space with
He++ cluster degrees of freedom largely solves this issue. We analyze
the role played by the -clustering and many-body correlations, and
study the dependence of the energy spectrum on the resolution scale of the
interaction.Comment: 5 pages, 4 figure
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