Nuclear Theory·nucl-th

Tuesday·July 26, 2016

15 papers—12 primary·3 cross-listed

01
[Submitted on 23 Jul 2016]
Nuclear Physics without High-Momentum Potentials: Direct Construction of the Effective Interaction from Scattering Observables
Kenneth S. McElvain · W. C. Haxton
The standard approach to nuclear physics encodes phase shift information in an NN potential, then decodes that information in forming an effective interaction, appropriate to a low-momentum Hilbert space. Here we show that it is instead possible to construct the effective interaction directly from continuum phase shifts and mixing angles, eliminating all reference to a high momentum potential. The theory is rapidly convergent and well behaved, yielding sub-keV accuracy.
Comments:
5 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat)
arXiv:
1607.06863 [pdf]
6 citations
02
[Submitted on 23 Jul 2016]
In-Medium Similarity Renormalization Group for Closed and Open-Shell Nuclei
H. Hergert🇺🇸
We present a pedagogical introduction to the In-Medium Similarity Renormalization Group (IM-SRG) framework for ab initio calculations of nuclei. The IM-SRG performs continuous unitary transformations of the nuclear many-body Hamiltonian in second-quantized form, which can be implemented with polynomial computational effort. Through suitably chosen generators, it is possible to extract eigenvalues of the Hamiltonian in a given nucleus, or drive the Hamiltonian matrix in configuration space to specific structures, e.g., band- or block-diagonal form. Exploiting this flexibility, we describe two complementary approaches for the description of closed- and open-shell nuclei: The first is the Multireference IM-SRG (MR-IM-SRG), which is designed for the efficient calculation of nuclear ground-state properties. The second is the derivation of nonempirical valence-space interactions that can be used as input for nuclear Shell model (i.e., configuration interaction (CI)) calculations. This IM-SRG+Shell model approach provides immediate access to excitation spectra, transitions, etc., but is limited in applicability by the factorial cost of the CI calculations. We review applications of the MR-IM-SRG and IM-SRG+Shell model approaches to the calculation of ground-state properties for the oxygen, calcium, and nickel isotopic chains or the spectroscopy of nuclei in the lower $s d$ shell, respectively, and present selected new results, e.g., for the ground- and excited state properties of neon isotopes.
Comments:
77 pages, 23 figures, invited comment for the Physica Scripta focus issue celebrating the 40-year anniversary of the 1975 Physics Nobel Prize to Bohr, Mottelson, and Rainwater (matches published version)
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1607.06882 [pdf]
Phys.Scripta(2017)·105 citations
03
[Submitted on 23 Jul 2016]
Formation of eta'(958) Meson Bound States by the 6Li(gamma,d) reaction
M. Miyatani🇯🇵 · N. Ikeno🇯🇵 · H. Nagahiro🇯🇵 · S. Hirenzaki🇯🇵
We have investigated the 6Li(gamma,d) reaction theoretically for the formation of the eta'(958) mesic nucleus close to the recoilless kinematics. We have developed the theoretical formula and reported the quantitative results of the formation spectra for various cases in this article. We have found that the formation cross sections are reduced by the effects of the fragile deuteron form factor.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1607.06915 [pdf]
EPJA(2016)·2 citations
04
[Submitted on 23 Jul 2016]
Manifestation of nuclear cluster structure in Coulomb sums
A.Yu. Buki · I.S. Timchenko
Experimental Coulomb sum values of 6^Li and 7^Li nuclei have been obtained, extending the earlier reported momentum transfer range of Coulomb sums for these nuclei up to q = 0.750 ... 1.625 fm^-1. The dependence of the Coulomb sums on the momentum transfers of 6^Li and 7^Li is shown to differ substantially from similar dependences for all the other nuclei investigated. Relationship between the nuclear cluster structure and Coulomb sums has been considered. The momentum transfer value, above which the Coulomb sum becomes constant, is found to be related to the cluster isolation parameter x, which characterizes the degree of nuclear clusterization.
Comments:
10 pages, 6 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1607.06920 [pdf]
0 citations
05
[Submitted on 23 Jul 2016]
Hartree-Fock-Bogoliubov calculation of ground state properties of even-even and odd Mo and Ru isotopes
Y. El Bassem · M. Oulne
In a previous work [Int. J. Mod. Phys. E 24, 1550073 (2015)], hereafter referred as paper I, we have investigated the ground-state properties of Nd, Ce and Sm isotopes within Hartree-Fock-Bogoliubov method with SLy5 skyrme force in which the pairing strength has been generalized with a new proposed formula. However, that formula is more appropriate for the region of Nd. In this work, we have studied the ground-state properties of both even-even and odd Mo and Ru isotopes. For this, we have used Hartree- Fock-Bogoliubov method with SLy4 skyrme force, and a new formula of the pairing strength which is more accurate for this region of nuclei. The results have been compared with available experimental data, the results of Hartree-Fock-Bogoliubov calculations based on the D1S Gogny effective nucleon-nucleon interaction and predictions of some nuclear models such as Finite Range Droplet Model (FRDM) and Relativistic Mean Field (RMF) theory.
Comments:
15 pages, 4 tables, 8 figures (accepted to be published in Nuclear Physics A). arXiv admin note: substantial text overlap with arXiv:1510.01785; text overlap with arXiv:1210.1825 by other authors
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1607.06941 [pdf]
NPA(2017)·25 citations
06
[Submitted on 24 Jul 2016]
Spectrum of shear modes in the neutron-star crust: Estimating the nuclear-physics uncertainties
Ingo Tews
I construct a model of the inner crust of neutron stars using interactions from chiral effective field theory (EFT) in order to calculate its equation of state (EOS), shear properties, and the spectrum of crustal shear modes. I systematically study uncertainties associated with the nuclear physics input, the crust composition, and neutron entrainment, and estimate their impact on crustal shear properties and the shear-mode spectrum. I find that the uncertainties originate mainly in two sources: The neutron-matter EOS and neutron entrainment. I compare the spectrum of crustal shear modes to observed frequencies of quasi-periodic oscillations in the afterglow of giant $γ$ -ray bursts and find that all of these frequencies could be described within uncertainties, which are, however, at present too sizable to infer neutron-star properties from observations.
Comments:
13 pages, 10 figures, published version
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
1607.06998 [pdf]
PRC(2017)·50 citations
07
[Submitted on 24 Jul 2016]
Cold nuclear matter effects and a modified form of the proximity approach
Reza Gharaei
The influence of the cold nuclear matter effects on the Coulomb barriers and also on the fusion cross sections of 47 fusion reactions are systematically investigated within the framework of the proximity formalism. For this purpose, I modify the original version of this formalism (Prox. 77) using a new analytical form of the universal function which is formulated based on the double-folding model with three density-dependent versions of the M3Y-type interactions, namely DDM3Y1, CDM3Y3 and BDM3Y1. It is found that when the Prox. 77 potential is accompanied by each of the formulated universal functions, the agreement between the theoretical and experimental data of the barrier height and also the fusion cross section increase for our selected fusion systems. The present study also provides appropriate conditions to explore theoretically the variation effects of the NM incompressibility constant $K$ on the calculated results caused by the Prox. 77 model. It is shown that the accuracy of this potential model for reproducing the experimental fusion data enhances by increasing the strength of this constant. A discussion is also presented about the role of various physical effects in the theoretical results of the proximity approach.
Comments:
25 pages, 6 figures and 3 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1607.07013 [pdf]
0 citations
08
[Submitted on 24 Jul 2016]
Enhanced collectivity of gamma vibration in neutron-rich Dy isotopes with N=108 - 110
Kenichi Yoshida · Hiroshi Watanabe
Background: The $γ$ vibrational mode of excitation is an acknowledged collective mode in deformed nuclei. The collectivity depends on the details of the shell structure around the Fermi levels, in particular the presence of the orbitals that have the enhanced transition matrix elements of the non-axial quadrupole excitation. Quite recently, a sudden decrease in the excitation energy of the $γ$ vibration was observed at RIKEN RIBF for the neutron-rich Dy isotopes at $N = 106$ . Purpose: In the present work, by studying systematically the microscopic structure of the $γ$ vibration in the neutron-rich Dy isotopes with $N = 98 - 114$ , we try to understand the mechanism of the observed softening. Methods: The low-frequency modes of excitation in the neutron-rich rare-earth nuclei are described based on nuclear density-functional theory. We employ the Skyrme energy-density functionals (EDF) in the Hartree-Fock-Bogoliubov calculation for the ground states and in the Quasiparticle Random-Phase Approximation (QRPA) for the excitations. Results: The lowering of the excitation energy around $N = 106$ is reproduced well by employing the SkM* and SLy4 functionals. We find the similar isotopic dependence of the excitation energy in the neutron-rich Er and Yb isotopes as well. Conclusions: The microscopic framework of the Skyrme-EDF based QRPA describes well the isotopic dependence of the energy of the $γ$ vibration in the well-deformed neutron-rich rare-earth nuclei. The strong collectivity at $N = 108 - 110$ is expected as the Fermi level of neutrons lies just among the orbitals that play an important role in generating the collectivity around $N = 106$ .
Comments:
7 pages, 5 figures, submitted to Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1607.07111 [pdf]
PTEP(2016)·5 citations
09
[Submitted on 25 Jul 2016]
Investigation of the $η^{'} N$ system using the linear sigma model
Shuntaro Sakai🇯🇵 · Daisuke Jido🇯🇵
In this paper, we investigate the $η^{'} N$ system using the three-flavor linear sigma model including the effect of flavor SU(3) symmetry breaking. The $η^{'} N$ bound state is also found in the case including flavor symmetry breaking and coupling with the $η N$ and $π N$ channels. The $η^{'} N$ interaction becomes more attractive with the inclusion of flavor symmetry breaking, which causes mixing between the singlet and octet scalar mesons. The existence of such a bound state would have some impact on the $η^{'}$ -nucleus system, which is of interest from both theoretical and experimental viewpoints.
Comments:
15 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1607.07116 [pdf]
PTEP(2017)·8 citations
10
[Submitted on 25 Jul 2016]
Effects of entrance channel on fusion probability in hot fusion reactions
Long Zhu · Jun Sun · Ching-Yuan Huang · Feng-Shou Zhang
Within the framework of the dinuclear system (DNS) model, the fusion reactions leading to the compound nuclei 274Hs and 286Cn are investigated. The fusion probability as a function of DNS excitation energy is studied. The calculated results are in good agreement with the available experimental data. The obtained results show that the fusion probabilities are obviously enhanced for the reactions located at high place in potential energy surface, although these reactions may have small values of mass asymmetry. It is found that the enhancement is due to the large potential energy of the initial DNS.
Comments:
Accepted in Chinese Physics C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1607.07148 [pdf]
CPC(2016)·6 citations
11
[Submitted on 25 Jul 2016]
Improved Numerical Generalization of Bethe- Weizsacker Mass Formula
Strachimir Mavrodiev
In this paper is presented explicit improved numerical generalization of Bethe-Weizsacker mass formulae which describes the values of measured 2654 nuclear mass in AME2012 nuclear database with accuracy less than 2.2 MeV, starting from the number of protons Z=1 and number of neutrons N=1. In the obtained generazation of the Bethe-Weizsacker formula the influence of magic numbers and boundaries of their influence between them is defined for nine proton (2, 8, 14, 20, 28, 50, 82, 108, 124) and ten neutron (2, 8, 14, 20, 28, 50, 82, 124, 152, 202) magic numbers.
Comments:
81 pages, 12 figures. arXiv admin note: text overlap with arXiv:1602.06777
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1607.07217 [pdf]
2 citations
12
[Submitted on 25 Jul 2016]
Cumulants and Correlation Functions vs the QCD phase diagram
Adam Bzdak🇵🇱 · Volker Koch🇺🇸 · Nils Strodthoff🇺🇸
In this paper we discuss the relation of particle number cumulants and correlation functions. It is argued that measuring couplings of the genuine multi-particle correlation functions could provide cleaner information on possible non-trivial dynamics in heavy-ion collisions. We extract integrated multi-proton correlation functions from the presently available experimental data on proton cumulants. We find that the STAR data contain significant four-proton correlations, at least at the lower energies, with indication of changing dynamics in central collisions. We also find that these correlations are rather long-ranged in rapidity. Finally, using the Ising model, we demonstrate how the signs of the multi-proton correlation functions may be used to exclude certain regions of the phase diagram close to the critical point.
Comments:
13 pages, 8 figures; PRC version, improved discussion
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1607.07375 [pdf]
PRC(2017)·89 citations
13
[Submitted on 22 Jul 2016] (cross-list from hep-ph)
Constraining Anomalous Forces with Pseudoscalar and Axial Couplings Employing a Spin-Independent Analysis
S. Aldaihan🇺🇸 · W.M. Snow🇺🇸 · D.E. Krause🇺🇸 · J.C. Long🇺🇸 · E. Fischbach🇺🇸
Present laboratory limits on the coupling strength of anomalous pseudoscalar and axial interactions are many orders of magnitude weaker than their scalar and vector analogs. Here we investigate two mechanisms which can circumvent this suppression and thereby lead to improved limits.
Comments:
Presented at the Seventh Meeting on CPT and Lorentz Symmetry, Bloomington, Indiana, June 20-24, 2016
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1607.06853 [pdf]
0 citations
14
[Submitted on 23 Jul 2016] (cross-list from nucl-ex)
Shape coexistence in 153Ho
Dibyadyuti Pramanik · S. Sarkar · M. Saha Sarkar · Abhijit Bisoi · Sudatta Ray · Shinjinee Dasgupta · A.Chakraborty · Krishichayan · Ritesh Kshetri · Indrani Ray · S. Ganguly · M. K. Pradhan and 10 other authors
The high-spin states in 153Ho, have been studied by 139 57 La(20Ne, 6n) reaction at a projectile energy of 139 MeV at Variable Energy Cyclotron Centre (VECC), Kolkata, India, utilizing an earlier campaign of Indian National Gamma Array (INGA) setup. Data from gamma-gamma coincidence, directional correlation and polarization measurements have been analyzed to assign and confirm the spins and parities of the levels. We have suggested a few additions and revisions of the reported level scheme of 153Ho. The RF-gamma time difference spectra have been useful to confirm the half-life of an isomer in this nucleus. From the comparison of experimental and theoretical results, it is found that there are definite indications of shape coexistence in this nucleus. The experimental and calculated lifetimes of several isomers have been compared to follow the coexistence and evolution of shape with increasing spin.
Comments:
Accepted for publication in Physical Review C as a regular article
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1607.06954 [pdf]
PRC(2016)·10 citations
15
[Submitted on 25 Jul 2016] (cross-list from cond-mat.supr-con)
$^{3} P_{2}$ Superfluids Are Topological
Takeshi Mizushima · Kota Masuda · Muneto Nitta
We clarify topology of $^{3} P_{2}$ superfluids which are expected to be realized in the inner cores of neutron stars and cubic odd-parity superconductors. $^{3} P_{2}$ phases include uniaxial/biaxial nematic phases and nonunitary ferromagnetic and cyclic phases. We here show that all the phases are accompanied by different types of topologically protected gapless fermions: Surface Majorana fermions in nematic phases and a quartet of (single) itinerant Majorana fermions in the cyclic (ferromagnetic) phase. Using the superfluid Fermi liquid theory, we also demonstrate that dihedral-two and -four biaxial nematic phases are thermodynamically favored in the weak coupling limit under a magnetic field. It is shown that the tricritical point exists on the phase boundary between these two phases and may be realized in the core of realistic magnetars. We unveil the intertwining of symmetry and topology behind mass acquisition of surface Majorana fermions in nematic phases.
Comments:
6 pages, 3 figures
Subjects:
Superconductivity (cond-mat.supr-con); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1607.07266 [pdf]
PRB(2017)·26 citations

Affiliations

first authorsco-authorsvia INSPIRE