Nuclear Theory·nucl-th

Thursday·November 19, 2015

11 papers—8 primary·3 cross-listed

01
[Submitted on 18 Nov 2015]
Systematic study of $α$ decay half-lives for even-even nuclei within a two-potential approach
Xiao-Dong Sun🇨🇳 · Ping Guo🇨🇳 · Xiao-Hua Li🇨🇳
$α$ decay is a common and important process for natural radioactivity of heavy and superheavy nuclei. The $α$ decay half-lives for even-even nuclei from Z=62 to Z=118 are systematically researched based on the two-potential approach with a quasi-stationary state approximation. To describe the deviations between experimental half-lives and calculated results due to the nuclear shell structure, a hindrance factor related with $α$ particle preformation probability is introduced. Our results can well reproduce the experimental data equally to the density-dependent cluster model and the generalized liquid drop model. We also study the isospin effect of nuclear potential in this work. Considering the isospin effect the calculated results improved about 7.3 $%$ .
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1511.05652 [pdf]
PRC(2016)·84 citations
02
[Submitted on 18 Nov 2015]
Multidimensionally-constrained relativistic Hartree-Bogoliubov study of nuclear spontaneous fission
Jie Zhao · Bing-Nan Lu · Tamara Niksic · Dario Vretenar
Recent microscopic studies, based on the theoretical framework of nuclear energy density functionals, have analyzed dynamic (least action) and static (minimum energy) fission paths, and it has been shown that in addition to the important role played by nonaxial and/or octupole collective degrees of freedom, fission paths crucially depend on the approximations adopted in calculating the collective inertia. The dynamics of spontaneous fission of $^{264}$ Fm and $^{250}$ Fm is explored. The fission paths, action integrals and the corresponding half-lives predicted by the functionals PC-PK1 and DD-PC1 are compared and, in the case of $^{264}$ Fm, discussed in relation with recent results obtained using the HFB model based on the Skyrme functional SkM $^{*}$ and a density dependent mixed pairing interaction. Deformation energy surfaces, collective potentials, and perturbative and nonperturbative cranking collective inertia tensors are calculated using the multidimensionally-constrained relativistic Hartree-Bogoliubov (MDC-RHB) model, with the energy density functionals PC-PK1 and DD-PC1. Pairing correlations are treated in the Bogoliubov approximation using a separable pairing force of finite range. The least-action principle is employed to determine dynamic spontaneous fission paths.
Comments:
Submitted to Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1511.05689 [pdf]
PRC(2015)·36 citations
03
[Submitted on 18 Nov 2015]
Recent developments in the eikonal description of the breakup of exotic nuclei
P. Capel · F. Colomer · H. Esbensen · T. Fukui · R.C. Johnson · F.M. Nunes · K. Ogata
The study of exotic nuclear structures, such as halo nuclei, is usually performed through nuclear reactions. An accurate reaction model coupled to a realistic description of the projectile is needed to correctly interpret experimental data. In this contribution, we briefly summarise the assumptions made within the modelling of reactions involving halo nuclei. We describe briefly the Continuum-Discretised Coupled Channel method (CDCC) and the Dynamical Eikonal Approximation (DEA) in particular and present a comparison between them for the breakup of 15C on Pb at 68AMeV. We show the problem faced by the models based on the eikonal approximation at low energy and detail a correction that enables their extension down to lower beam energies. A new reaction observable is also presented. It consists of the ratio between angular distributions for two different processes, such as elastic scattering and breakup. This ratio is completely independent of the reaction mechanism and hence is more sensitive to the projectile structure than usual reaction observables, which makes it a very powerful tool to study exotic structures far from stability.
Comments:
Contribution to the proceedings of the XXI International School on Nuclear Physics and Applications & the International Symposium on Exotic Nuclei, dedicated to the 60th Anniversary of the JINR (Dubna) (Varna, Bulgaria, 6-12 September 2015), 7 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1511.05729 [pdf]
J.Phys.Conf.Ser.(2016)·1 citation
04
[Submitted on 18 Nov 2015]
Simultaneous occurrence of distinct symmetries in nuclei
A. Leviatan
We show that distinct emergent symmetries, such as partial dynamical symmetry and quasi dynamical symmetry, can occur simultaneously in the same or different eigenstates of the Hamiltonian. Implications for nuclear spectroscopy in the rare-earth region and for first-order quantum phase transitions between spherical and deformed shapes, are considered.
Comments:
7 pages, 6 figures, Final version, Proc. XXI Int. School on Nuclear Physics and Applications & Int. Symposium on Exotic Nuclei (ISEN-2015), September 6-12, 2015, Varna, Bulgaria
Subjects:
Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
1511.05848 [pdf]
J.Phys.Conf.Ser.(2016)·0 citations
05
[Submitted on 18 Nov 2015]
Strangeness S=-2 baryon-baryon interaction at next-to-leading order in chiral effective field theory
J. Haidenbauer🇩🇪 · Ulf-G. Meißner🇩🇪 · S. Petschauer🇩🇪
The strangeness $S = - 2$ baryon-baryon interaction is studied in chiral effective field theory up to next-to-leading order. The potential at this order consists of contributions from one- and two-pseudoscalar-meson exchange diagrams and from four-baryon contact terms without and with two derivatives. SU(3) flavor symmetry is imposed for constructing the interaction in the $S = - 2$ sector. Specifically, the couplings of the pseudoscalar mesons to the baryons are fixed by SU(3) symmetry and, in general, also the contact terms are related via SU(3) symmetry to those determined in a previous study of the $S = - 1$ hyperon-nucleon interaction. The explicit SU(3) symmetry breaking due to the physical masses of the pseudoscalar mesons ( $π$ , $K$ , $η$ ) is taken into account. It is argued that the $Ξ N$ interaction has to be relatively weak to be in accordance with available experimental constraints. In particular, the published values and upper bounds for the $Ξ^{-} p$ elastic and inelastic cross sections apparently rule out a somewhat stronger attractive $Ξ N$ force and, specifically, disfavor any near-threshold deuteron-like bound states in that system.
Comments:
17 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1511.05859 [pdf]
NPA(2016)·115 citations
06
[Submitted on 18 Nov 2015]
Excluded volume effects in the hybrid star EoS
D. E. Alvarez-Castillo🇷🇺 · M. A. R. Kaltenborn🇵🇱 · D. Blaschke🇷🇺
In this contribution, we outline a new 2-phase description of the quark-nuclear matter hybrid equation of state that takes into account effects of phase space occupation (excluded volume) in both, the hadronic and the quark matter phases. For the nuclear matter phase, the reduction of the available volume at increasing density leads to a stiffening, while for the quark matter phase a reduction of the effective string tension in the confining density functional is obtained. The deconfinement phase transition in the resulting hybrid equation of state is sensitive to both excluded volume effects. As an application, we consider matter under compact star constraints of electric neutrality and $β$ -equilibrium. We obtain mass-radius relations for hybrid stars that fulfill the $2 M_{⊙}$ constraint and exhibit the high-mass twin phenomenon. Both features depend sensitively on the excluded volume.
Comments:
4 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1511.05873 [pdf]
J.Phys.Conf.Ser.(2016)·4 citations
07
[Submitted on 18 Nov 2015]
Mass-radius constraints for the neutron star EoS - Bayesian analysis
A. Ayriyan🇷🇺 · D. E. Alvarez-Castillo🇷🇺 · D. Blaschke🇲🇽 · H. Grigorian🇷🇺
We suggest a new Bayesian analysis (BA) using disjunct M-R constraints for extracting probability measures for cold, dense matter equations of state (EoS). One of the key issues of such an analysis is the question of a deconfinement transition in compact stars and whether it proceeds as a crossover or rather as a first order transition. We show by postulating results of not yet existing radius measurements for the known pulsars with a mass of $2 M_{⊙}$ that a radius gap of about 3 km would clearly select an EoS with a strong first order phase transition as the most probably one. This would support the existence of a critical endpoint in the QCD phase diagram under scrutiny in present and upcoming heavy-ion collision experiments.
Comments:
4 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1511.05880 [pdf]
J.Phys.Conf.Ser.(2016)·9 citations
08
[Submitted on 18 Nov 2015]
Towards a new quark-nuclear matter EoS for applications in astrophysics and heavy-ion collisions
N.-U. Bastian🇵🇱 · D. Blaschke🇵🇱
The aim of our work is to develop a unified equation of state (EoS) for nuclear and quark matter for a wide range in temperature, density and isospin so that it becomes applicable for heavy-ion collisions as well as for the astrophysics of neutron stars, their mergers and supernova explosions. As a first step, we use improved EoS for the hadronic and quark matter phases and join them via Maxwell construction. We discuss the limitations of a 2-phase description and outline steps beyond it, towards the formulation of a unified quark-nuclear matter EoS on a more fundamental level by a cluster virial expansion.
Comments:
4 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1511.05881 [pdf]
J.Phys.Conf.Ser.(2016)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE