Nuclear Theory·nucl-th

Monday·October 23, 2017

10 papers—4 primary·6 cross-listed

01
[Submitted on 19 Oct 2017]
Three-cluster dynamics within the ab initio no-core shell model with continuum: How many-body correlations and $α$ -clustering shape $^{6}$ He
Sofia Quaglioni (1) · Carolina Romero-Redondo (1) · Petr Navratil (2) · Guillaume Hupin (3) ((1) Lawrence Livermore National Laboratory, (2) TRIUMF, (3) CEA, DAM, DIF)
We realize the treatment of bound and continuum nuclear systems in the proximity of a three-body breakup threshold within the ab initio framework of the no-core shell model with continuum. Many-body eigenstates obtained from the diagonalization of the Hamiltonian within the harmonic-oscillator expansion of the no-core shell model are coupled with continuous microscopic three-cluster states to correctly describe the nuclear wave function both in the interior and asymptotic regions. We discuss the formalism in detail and give algebraic expressions for the case of core+ $n$ + $n$ systems. Using similarity-renormalization-group evolved nucleon-nucleon interactions, we analyze the role of $^{4}$ He+ $n$ + $n$ clustering and many-body correlations in the ground and low-lying continuum states of the Borromean $^{6}$ He nucleus, and study the dependence of the energy spectrum on the resolution scale of the interaction. We show that $^{6}$ He small binding energy and extended radii compatible with experiment can be obtained simultaneously, without recurring to extrapolations. We also find that a significant portion of the ground-state energy and the narrow width of the first $2^{+}$ resonance stem from many-body correlations that can be interpreted as core-excitation effects.
Comments:
25 pages, 14 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1710.07326 [pdf]
PRC(2018)·30 citations
02
[Submitted on 18 Oct 2017]
Nuclear medium effects in muonic neutrino interaction with energies from 0.2 GeV to 1.5 GeV
D. Vargas🇧🇷 · A.R. Samana🇧🇷 · F.G. Velasco🇧🇷 · O.R. Hoyos🇧🇷 · F. Guzmán🇧🇷 · J.L. Bernal-Castillo🇧🇷 · E. Andrade-II🇧🇷 · R. Perez🇧🇷 · A. Deppman🇧🇷 · C.A. Barbero🇦🇷 · A.E. Mariano🇦🇷
Nuclear reactions induced by muon neutrino with energies in the range from 0.2 to 1.5 GeV in Monte Carlo calculations framework in the intra-nuclear cascade model are studied. This study was done by comparison between the available experimental data and theoretical values of total cross section, and the energy distribution of emitted lepton energy in the reaction muon neutrino-nucleus, using the targets: $^{12}$ C, $^{16}$ O, $^{27}$ Al, $^{40}$ Ar, $^{56}$ Fe and $^{208}$ Pb. A phenomenological toy model of primary neutrino-nucleon interaction gives a good agreement of our theoretical inclusive neutrino nucleus cross in comparison with the available experimental data. Some interesting results on the behavior of the cross section as function of 1p-1n and higher contributions are also sketched. The previous results on the percentage of fake events related in available experiments in $^{12}$ C were expanded for the set studied nuclei. With the increase of mass target, the nuclear effects in the cross sections were observed along with the importance to take into account fake events in the reactions.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1710.07351 [pdf]
PRC(2017)·3 citations
03
[Submitted on 20 Oct 2017]
Comparison between the Lipkin-Nogami and Richardson solutions with complex single particle energy in the Lipkin's model
R. M. Id Betan
The pairing interaction is one of the most important contribution of the residual interaction and then, it is of major importance for the study of many-body systems. One can get solutions of the pairing Hamiltonian throught the Bardeen-Cooper-Schieffer (BCS) or the Lipkin-Nogami (LN) approximations but, the pairing Hamiltonian admit exact solution worked out by Richardson. Nuclei far away from the stability line have important correlations with the continuum part of the energy spectrum, due that the Fermi level is very close to the contiuum thershold. The correlations with the continuum can be included in the many-body description through the complex energy states, called Gamow states. In this work we compare the approximates and exact solutions of the pairing Hamiltonian in real and complex-energy representations. In the application of this formulation to the symmetric Lipkin model, we found that the LN solution is in a good agreement with the exact one; besides, the extension of the BCS solution to the complex energy plane gives solution even for strength below the critical one, which is purely imaginary.
Comments:
Published in the Anales de la Asociación Física Argentina. Vol. 28 N. 3, 87 (2017). six pages, seven figures, twenty references. Keywords: Lipkin-Nogami, Richardson, complex energy, Lipkin model, exact solution, pairing
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1710.07570 [pdf]
Anales AFA Vol. 28 Nro. 3, 87 (2017)·0 citations
04
[Submitted on 20 Oct 2017]
Fully coupled-channel study of $K^{-} pp$ resonance in a chiral SU(3)-based $K ˉ N$ potential
Akinobu Doté🇯🇵 · Takashi Inoue🇯🇵 · Takayuki Myo🇯🇵
We have investigated the most essential kaonic nucleus " $K^{-} pp$ " as a resonant state of the $K ˉ N N$ - $π Σ N$ - $π Λ N$ coupled channel system using a chiral SU(3)-based $K ˉ N$ potential. We treat the " $K^{-} pp$ " resonance adequately with a fully coupled-channel complex scaling method (full ccCSM). Self-consistency needs to be considered for the energy dependence of the chiral SU(3)-based potential. In the present study, we propose a simple prescription for the treatment of self-consistency, considering the {\it averaged threshold} and {\it averaged binding energy of mesons}. With this prescription, we have successfully found the self-consistent solutions of the " $K^{-} pp$ " three-body resonance. The results indicate that the " $K^{-} pp$ " system is bound rather shallowly. In particular, when the potential parameters are constrained with the latest $K ˉ N$ scattering length, the binding energy and half of the mesonic decay width are obtained as $14 - 50$ MeV and $8 - 19$ MeV, respectively.
Comments:
7 pages, 2 figures, accepted by Phys. Lett. B
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1710.07589 [pdf]
PLB(2018)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE

Three-cluster dynamics within the ab initio no-core shell model with continuum: How many-body correlations and α-clustering shape 6He

Nuclear medium effects in muonic neutrino interaction with energies from 0.2 GeV to 1.5 GeV

Comparison between the Lipkin-Nogami and Richardson solutions with complex single particle energy in the Lipkin's model

Fully coupled-channel study of K−pp resonance in a chiral SU(3)-based KˉN potential

Affiliations

Three-cluster dynamics within the ab initio no-core shell model with continuum: How many-body correlations and $α$ -clustering shape $^{6}$ He

Fully coupled-channel study of $K^{-} pp$ resonance in a chiral SU(3)-based $K ˉ N$ potential