Nuclear Theory·nucl-th

Monday·June 13, 2016

10 papers—5 primary·5 cross-listed

01
[Submitted on 9 Jun 2016]
Dependence of two-proton radioactivity on nuclear pairing models
Tomohiro Oishi · Markus Kortelainen · Alessandro Pastore
Sensitivity of two-proton emitting decay to nuclear pairing correlation is discussed within a time-dependent three-body model. We focus on the $^{6}$ Be nucleus assuming $α + p + p$ configuration, and its decay process is described as a time-evolution of the three-body resonance state. For a proton-proton subsystem, a schematic density-dependent contact (SDDC) pairing model is employed. From the time-dependent calculation, we observed the exponential decay rule of a two-proton emission. It is shown that the density dependence does not play a major role in determining the decay width, which can be controlled only by the asymptotic strength of the pairing interaction. This asymptotic pairing sensitivity can be understood in terms of the dynamics of the wave function driven by the three-body Hamiltonian, by monitoring the time-dependent density distribution. With this simple SDDC pairing model, there remains an impossible trinity problem: it cannot simultaneously reproduce the empirical $Q$ value, decay width, and the nucleon-nucleon scattering length. This problem suggests that a further sophistication of the theoretical pairing model is necessary, utilizing the two-proton radioactivity data as the reference quantities.
Comments:
Result and conclusion have been majorly revised from the previous version. 11 pages, 10 figures, 2 table
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1606.03111 [pdf]
PRC(2017)·29 citations
02
[Submitted on 10 Jun 2016]
Quark-Meson Coupling model based upon the Nambu-Jona Lasinio model
D. L. Whittenbury🇦🇺 · M. E. Carrillo-Serrano🇦🇺 · A. W. Thomas🇦🇺
The NJL model for the octet baryons, using proper time regularization to simulate some of the features of confinement, is solved self-consistently in nuclear matter. This provides an alternative framework to the MIT bag model which has been used in the quark-meson coupling model. After fitting the parameters of the model to the saturation properties of symmetric nuclear matter the model is used to explore the equation of state of pure neutron matter as well as nuclear matter at densities relevant to heavy ion collisions. With a view to future studies of high mass neutron stars, the binding of hyperons is also explored.
Comments:
7 pages and 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1606.03158 [pdf]
PLB(2016)·5 citations
03
[Submitted on 10 Jun 2016]
Solutions of random-phase approximation equation for positive-semidefinite stability matrix
H. Nakada
It is mathematically proven that, if the stability matrix $S$ is positive-semidefinite, solutions of the random-phase approximation (RPA) equation are all physical or belong to Nambu-Goldstone (NG) modes, and the NG-mode solutions may form Jordan blocks of $N S$ ( $N$ is the norm matrix) but their dimension is not more than two. This guarantees that the NG modes in the RPA can be separated out via canonically conjugate variables.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1606.03167 [pdf]
1 citation
04
[Submitted on 10 Jun 2016]
Can realistic interaction be useful for nuclear mean-field approaches?
H. Nakada🇯🇵 · K. Sugiura🇯🇵 · T. Inakura🇯🇵 · J. Margueron🇫🇷
Recent applications of the M3Y-type semi-realistic interaction to the nuclear mean-field approaches are presented: (i) Prediction of magic numbers and (ii) isotope shifts of nuclei with magic proton numbers. The results exemplify that realistic interaction, which is derived from the base $2 N$ and $3 N$ interaction, furnish a new theoretical instrument for advancing nuclear mean-field approaches.
Comments:
9 pages including 6 figures, published in EPJA 52, 185 (2016)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1606.03169 [pdf]
EPJA(2016)·1 citation
05
[Submitted on 10 Jun 2016]
Radii in the $s d$ shell and the $s_{1/2}$ "halo" orbit: A game changer
J. Bonnard🇮🇹 · A. P. Zuker🇮🇹
Proton radii of nuclei in the $s d$ shell depart appreciably from the asymptotic law, $ρ_{π} = ρ_{0} A^{1/3}$ . The departure exhibits systematic trends fairly well described by a single phenomenological term in the Duflo-Zuker formulation, which also happens to explain the sudden increase in slope in the isotope shifts of several chains at neutron number $N = 28$ . It was recently shown that this term is associated with the abnormally large size of the $s_{1/2}$ and $p$ orbits in the $s d$ and $p f$ shells respectively. Further to explore the problem, we propose to calculate microscopically radii in the former. Since the (square) radius is basically a one body operator, its evolution is dictated by single particle occupancies determined by shell model calculations. Assuming that the departure from the asymptotic form is entirely due to the $s_{1/2}$ orbit, the expectation value $⟨ s_{1/2} ∣ r^{2} ∣ s_{1/2} ⟩$ is determined by demanding that its evolution be such as to describe well nuclear radii. It does, for an orbit that remains very large (about 1.6 fm bigger than its $d$ counterparts) up to $N, Z = 14$ then drops abruptly but remains some 0.6 fm larger than the $d$ orbits. An unexpected behavior bound to challenge our understanding of shell formation.
Comments:
4 pages 6(7) figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1606.03345 [pdf]
J.Phys.Conf.Ser.(2018)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE

Dependence of two-proton radioactivity on nuclear pairing models

Quark-Meson Coupling model based upon the Nambu-Jona Lasinio model

Solutions of random-phase approximation equation for positive-semidefinite stability matrix

Can realistic interaction be useful for nuclear mean-field approaches?

Radii in the sd shell and the s1/2​ "halo" orbit: A game changer

Affiliations

Radii in the $s d$ shell and the $s_{1/2}$ "halo" orbit: A game changer