Nuclear Theory·nucl-th

Tuesday·July 4, 2017

13 papers—8 primary·5 cross-listed

01
[Submitted on 1 Jul 2017]
Equilibrium nuclear ensembles taking into account vaporization of hot nuclei in dense stellar matter
Shun Furusawa · Igor Mishustin
We investigate the high-temperature effect on the nuclear matter that consists of mixture of nucleons and all nuclei in the dense and hot stellar environment. The individual nuclei are described within the compressible liquid-drop model that is based on Skyrme interactions for bulk energies and that takes into account modifications of the surface and Coulomb energies at finite temperatures and densities. The free-energy density is minimized with respect to the individual equilibrium densities of all heavy nuclei and the nuclear composition. We find that their optimized equilibrium densities become smaller and smaller at high temperatures because of the increase of thermal contributions to bulk free energies and the reduction of surface energies. The neutron-rich nuclei become unstable and disappear one after another at some temperatures. The calculations are performed for two sets of model parameters leading to different values of the slope parameter in the nuclear symmetry energy. It is found that the larger slope parameter reduces the equilibrium densities and the melting temperatures. We also compare the new model with some other approaches and find that the mass fractions of heavy nuclei in the previous calculations that omit vaporization are underestimated at $T ≲ 10$ MeV and overestimated at $T ≳ 10$ ~MeV. The further sophistication of calculations of nuclear vaporization and of light clusters would be required to construct the equation of state for explosive astrophysical phenomena.
Comments:
27pages, 8 figures, accepted for publication in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1707.00147 [pdf]
PRC(2018)·8 citations
02
[Submitted on 2 Jul 2017]
Structure of krypton isotopes within the interacting boson model derived from the Gogny energy density functional
K. Nomura · R. Rodríguez-Guzmán · Y. M. Humadi · L. M. Robledo · H. Abusara
The evolution and coexistence of the nuclear shapes as well as the corresponding low-lying collective states and electromagnetic transition rates are investigated along the Krypton isotopic chain within the framework of the interacting boson model (IBM). The IBM Hamiltonian is determined through mean-field calculations based on the several parametrizations of the Gogny energy density functional and the relativistic mean-field Lagrangian. The mean-field energy surfaces, as functions of the axial $β$ and triaxial $γ$ quadrupole deformations, are mapped onto the expectation value of the interacting-boson Hamiltonian that explicitly includes the particle-hole excitations. The resulting boson Hamiltonian is then used to compute low-energy excitation spectra as well as E2 and E0 transition probabilities for $^{70 - 100}$ Kr. Our results point to a number of examples of the prolate-oblate shape transitions and coexistence both on the neutron-deficient and neutron-rich sides. A reasonable agreement with the available experimental data is obtained for the considered nuclear properties.
Comments:
13 pages, 9 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1707.00236 [pdf]
PRC(2017)·26 citations
03
[Submitted on 2 Jul 2017]
Research on the halo in $^{31}$ Ne with complex momentum representation method
Ya-Juan Tian · Quan Liu · Tai-Hua Heng · Jian-You Guo
Halo is one of the most interesting phenomena in exotic nuclei especially for $^{31}$ Ne, which is deemed to be a halo nucleus formed by a $p -$ wave resonance. However, the theoretical calculations don't suggest a $p -$ wave resonance using the scattering phase shift approach or complex scaling method. Here, we apply the complex momentum representation method to explore resonances in $^{31}$ Ne. We have calculated the single-particle energies for bound and resonant states together with their evolutions with deformation. The results show that the $p -$ wave resonances appear clearly in the complex momentum plane accompanied with the $p - f$ inversion in the single-particle levels. As it happens the $p - f$ inversion, the calculated energy, width, and occupation probabilities of major components in the level occupied by valance neutron support a $p -$ wave halo for $^{31}$ Ne.
Comments:
7pages,8figres
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1707.00246 [pdf]
PRC(2017)·19 citations
04
[Submitted on 2 Jul 2017]
General formalism of collective motion for any deformed system
Jian-You Guo
Based on Bohr model, we have presented a general formalism describing the collective motion for any deformed system, in which the collective Hamiltonian is expressed as vibrations in the body-fixed frame, rotation of whole system around the laboratory frame, and coupling between vibrations and rotation. Under the condition of decoupling approximation, we have derived the quantized Hamiltonian operator. Based on the operator, we have calculated the rotational spectra for some special octupole and hexadecapole deformed systems, and shown their dependencies on deformation. The result indicates that the contribution of octupole or hexadecapole deformations to the lowest band is regular, while that to higher bands is dramatic. These features reflecting octupole and hexadecapole deformations are helpful to recognize the properties of real nuclei with octupole and/or hexadecapole deformations coexisting with quadrupole deformations.
Comments:
10pages,4figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1707.00247 [pdf]
PRC(2015)·4 citations
05
[Submitted on 2 Jul 2017]
The Spin and Orbital Contributions to Magnetic Dipole Transitions
Arun Kingan · Michael Quinonez · Xiaofei Yu · Larry Zamick
In previous works we examined they systematics of magnetic dipole transitions in a single j shell. We here extend the study to large space calculations.We consider the nuclei $^{44}$ Ti, $^{46}$ Ti and $^{48}$ C. Of particular interest is the contributions to B(M1) of the spin and orbital parts of the magnetic dipole operator. Whereas usual scissors mode analyses have as an initial state the J=0+ ground state (of an even-even nucleus) we here start with the lowest J=1+ T=1 state. This enables us to reach many more states e.g. J=2,T=0,1, and 2 and thus getter a better picture of the collectivity of this state.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1707.00266 [pdf]
IJMPE(2018)·9 citations
06
[Submitted on 2 Jul 2017]
Semiclassical triton
Nishchal R. Dwivedi · Harjeet Kaur · Sudhir R. Jain
The symmetric components of the spatial part of $S$ - and $D$ - states' wavefunctions for triton $(^{3} H)$ are investigated utilizing semiclassical expansion (in the powers of $ℏ$ ). Analysis of the diagonalized Hamiltonian reveals the existence of two different mass states within the ground state of triton. We have solved the coupled differential equations for the two admixed states $^{2} S_{1/2}$ and $^{4} D_{1/2}$ owing to tensor interactions exploiting classical WKB-theory using phenomenological Feshbach-Pease potentials. The relative probability of the $D$ -state is found to be in good agreement with the experimentally inferred value (4 - 5 \%).
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1707.00307 [pdf]
EPJA(2018)·7 citations
07
[Submitted on 3 Jul 2017]
Odd J states of isospin zero and one for 4 nucleon systems: near degeneracies
Arun Kingan · Larry Zamick
In this work we calculate the energies odd J $^{+}$ states in selectedeven-even nuclei- $^{44}$ Ti $^{52}$ Fe and $^{96}$ Cd. Of particularinterest is the fact that in many cases the first T=0 and the first T=1 state are close in energy. Whether the lowest odd J state hasT=0 or T=1 is here considered.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1707.00556 [pdf]
PRC(2018)·1 citation
08
[Submitted on 19 Jun 2017]
Smoothed square well potential
Péter Salamon · Tamás Vertse
The classical square well potential is smoothed with a finite range smoothing function in order to get a new simple strictly finite range form for the phenomenological nuclear potential. The smoothed square well form becomes exactly zero smoothly at a finite distance, in contrast to the Woods-Saxon form. If the smoothing range is four times the diffuseness of the Woods-Saxon shape both the central and the spin-orbit terms of the Woods-Saxon shape are reproduced reasonably well. The bound single particle energies in a Woods-Saxon potential can be well reproduced with those in the smoothed square well potential. The same is true for the complex energies of the narrow resonances.
Comments:
2 fig
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1707.00620 [pdf]
EPJA(2017)·2 citations
09
[Submitted on 30 Jun 2017] (cross-list from hep-ph)
Probing the hot and dense nuclear matter with $K^{*}, K ˉ^{*}$ vector mesons
Andrej Ilner🇩🇪 · Justin Blair🇺🇸 · Daniel Cabrera🇪🇸 · Christina Markert🇺🇸 · Elena Bratkovskaya🇩🇪
We investigate probing the hot and dense nuclear matter with strange vector mesons ( $K^{*}, K ˉ^{*}$ ). Our analysis is based on PHSD which incorporates partonic and hadronic dof and describes the full dynamics of HICs. This allows to study the $K^{*}$ and $K ˉ^{*}$ meson formation from the QGP and the in-medium effects related to the modification of their properties during the propagation in dense and hot matter. We employ relativistic Breit-Wigner spectral functions for the $K^{*}, K ˉ^{*}$ mesons with self-energies obtained from a G-matrix approach to study the role of in-medium effects on the $K^{*}$ and $K ˉ^{*}$ meson dynamics in HIC from FAIR/NICA to LHC energies. According to our analysis most of the final $K^{*} / K ˉ^{*}$ s, that can be observed experimentally, are produced during the late hadronic phase and stem dominantly from the $K (K ˉ) + π \to K^{*} (K ˉ^{*})$ formation channel. The amount of $K^{*} / K ˉ^{*}$ s originating from the QGP channel is comparatively small even at LHC energies and such $K^{*} / K ˉ^{*}$ s can hardly be reconstructed experimentally due to the rescattering of final pions and (anti-)kaons. This mirrors the results from our previous study on the strange vector-meson production in HICs at RHIC energies. The influence of the in-medium effects on the dynamics of the $K^{*} / K ˉ^{*}$ is rather small since they are mostly produced at low baryon densities. Additional cuts on the shape of the observed signal and the range of the invariant mass region of the $K^{*} / K ˉ^{*}$ also affect the final spectra. We demonstrate that the $K^{*} / K ˉ^{*}$ in-medium effects are more visible at lower beam energy, e.g. FAIR/NICA and BES RHIC energies, where the production of $K^{*} / K ˉ^{*}$ s occurs at larger baryon densities. Finally, we present the experimental procedures to extract information on the in-medium masses and widths by fitting final mass spectra at LHC energies.
Comments:
24 pages, 34 figures, extended version as published in Phys. Rev. C
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1707.00060 [pdf]
PRC(2019)·31 citations
10
[Submitted on 1 Jul 2017] (cross-list from hep-ph)
Study of the in-medium nucleon electromagnetic form factors using a light-front nucleon wave function combined with the quark-meson coupling model
W. R. B. de Aráujo (Secretaria de Educaçao do Estado de São Paulo)🇧🇷 · J.P. B. C. de Melo🇧🇷 · K. Tsushima (Laboratório de Física Teórica e Computacional, Universidade Cruzeiro do Sul)🇧🇷
We study the nucleon electromagnetic (EM) form factors in symmetric nuclear matter as well as in vacuum within a light-front approach using the in-medium inputs calculated by the quark-meson coupling model. The same in-medium quark properties are used as those used for the study of in-medium pion properties. The zero of the proton EM form factor ratio in vacuum, the electric to magnetic form factor ratio $μ_{p} G_{E p} (Q^{2}) / G_{M p} (Q^{2})$ ( $Q^{2} = - q^{2} > 0$ with $q$ being the four-momentum transfer), is determined including the latest experimental data by implementing a hard constituent quark component in the nucleon wave function. A reasonable fit is achieved for the ratio $μ_{p} G_{E p} (Q^{2}) / G_{M p} (Q^{2})$ in vacuum, and we predict that the $Q_{0}^{2}$ value to cross the zero of the ratio to be about 15 GeV $^{2}$ . In addition the double ratio data of the proton EM form factors in $^{4}$ He and H nuclei, $[G_{E p}^{^{4} He} (Q^{2}) / G_{M p}^{^{4} He} (Q^{2})] / [G_{E p}^{^{1} H} (Q^{2}) / G_{M p}^{^{1} H} (Q^{2})]$ , extracted by the polarized ( $e, e^{'} p$ ) scattering experiment on $^{4}$ He at JLab, are well described. We also predict that the $Q_{0}^{2}$ value satisfying $μ_{p} G_{E p} (Q_{0}^{2}) / G_{M p} (Q_{0}^{2}) = 0$ in symmetric nuclear matter, shifts to a smaller value as increasing nuclear matter density, which reflects the facts that the faster falloff of $G_{E p} (Q^{2})$ as increasing $Q^{2}$ and the increase of the proton mean-square charge radius. Furthermore, we calculate the neutron EM form factor double ratio in symmetric nuclear matter for $0.1 < Q^{2} < 1.0$ GeV $^{2}$ . The result shows that the neutron double ratio is enhanced relative to that in vacuum, while for the proton it is quenched, and agrees with an existing theoretical prediction.
Comments:
39 pages, 11 figures. Revtex style. Title change, and news results added. To appear Nuclear Physics A
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1707.00168 [pdf]
NPA(2018)·14 citations
11
[Submitted on 2 Jul 2017] (cross-list from physics.chem-ph)
Addition and removal energies of circular quantum dots
Fei Yuan · Samuel J. Novario · Nathan M. Parzuchowski · Sarah Reimann · S. K. Bogner · Morten Hjorth-Jensen
We present and compare several many-body methods as applied to two-dimensional quantum dots with circular symmetry. We calculate the approximate ground state energy using a harmonic oscillator basis optimized by Hartree-Fock (HF) theory and further improve the ground state energy using two post-HF methods: in-medium similarity renormalization group (IM-SRG) and coupled cluster with singles and doubles (CCSD). With the application of quasidegenerate perturbation theory (QDPT) or the equations-of-motion (EOM) method to the results of the previous two methods, we obtain addition and removal energies as well. Our results are benchmarked against full configuration interaction (FCI) and diffusion Monte Carlo (DMC) where available. We examine the rate of convergence and perform extrapolations to the infinite basis limit using a power-law model.
Comments:
45 pages, 11 figures. v2: Prune background theory + minor fixes based on review
Subjects:
physics.chem-ph (physics.chem-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Nuclear Theory (nucl-th)
arXiv:
1707.00229 [pdf]
J.Chem.Phys.(2017)·2 citations
12
[Submitted on 3 Jul 2017] (cross-list from astro-ph.HE)
Axion Production from Landau Quantization in the Strong Magnetic Field of Magnetars
Tomoyuki Maruyama🇯🇵 · A. Baha Balantekin🇯🇵 · Myung-Ki Cheoun🇯🇵 · Toshitaka Kajino🇨🇳 · Grant J. Mathews🇺🇸
We utilize an exact quantum calculation to explore axion emission from electrons and protons in the presence of the strong magnetic field of magnetars. The axion is emitted via transitions between the Landau levels generated by the strong magnetic field. The luminosity of axions emitted by protons is shown to be much larger than that of electrons and becomes stronger with increasing matter density. Cooling by axion emission is shown to be much larger than neutrino cooling by the Urca processes. Consequently, axion emission in the crust may significantly contribute to the cooling of magnetars. In the high-density core, however, it may cause heating of the magnetar.
Comments:
14 pages, 3 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1707.00384 [pdf]
PLB(2018)·14 citations
13
[Submitted on 3 Jul 2017] (cross-list from hep-th)
Stiff phases in strongly coupled gauge theories with holographic duals
Christian Ecker🇦🇹 · Carlos Hoyos🇪🇸 · Niko Jokela🇫🇮 · David Rodríguez Fernández🇪🇸 · Aleksi Vuorinen🇫🇮
According to common lore, Equations of State of field theories with gravity duals tend to be soft, with speeds of sound either below or around the conformal value of $v_{s} = 1/ 3$ . This has important consequences in particular for the physics of compact stars, where the detection of two solar mass neutron stars has been shown to require very stiff equations of state. In this paper, we show that no speed limit exists for holographic models at finite density, explicitly constructing examples where the speed of sound becomes arbitrarily close to that of light. This opens up the possibility of building hybrid stars that contain quark matter obeying a holographic equation of state in their cores.
Comments:
22 pages+appendices, 12 figures
Subjects:
High Energy Physics — Theory (hep-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1707.00521 [pdf]
JHEP(2017)·62 citations

Affiliations

first authorsco-authorsvia INSPIRE