Nuclear Theory·nucl-th

Thursday·November 14, 2019

11 papers—8 primary·3 cross-listed

01
[Submitted on 12 Nov 2019]
Elastic electromagnetic form factors of vector mesons
Yin-Zhen Xu🇨🇳 · Daniele Binosi🇮🇹 · Zhu-Fang Cui🇨🇳 · Bo-Lin Li🇨🇳 · Craig D Roberts🇨🇳 · Shu-Sheng Xu🇨🇳 · Hong-Shi Zong🇨🇳
A symmetry-preserving approach to the two valence-body continuum bound-state problem is used to calculate the elastic electromagnetic form factors of the $ρ$ -meson and subsequently to study the evolution of vector-meson form factors with current-quark mass. To facilitate a range of additional comparisons, $K^{*}$ form factors are also computed. The analysis reveals that: vector mesons are larger than pseudoscalar mesons; composite vector mesons are non-spherical, with magnetic and quadrupole moments that deviate $\sim 30$ \% from point-particle values; in many ways, vector-meson properties are as much influenced by emergent mass as those of pseudoscalars; and vector meson electric form factors possess a zero at spacelike momentum transfer. Qualitative similarities between the electric form factors of the $ρ$ and the proton, $G_{E}^{p}$ , are used to argue that the character of emergent mass in the Standard Model can force a zero in $G_{E}^{p}$ . Morover, the existence of a zero in vector meson electric form factors entails that a single-pole vector meson dominance model can only be of limited use in estimating properties of off-shell vector mesons, providing poor guidance for systems in which the Higgs-mechanism of mass generation is dominant.
Comments:
11 pages, 5 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1911.05199 [pdf]
PRD(2019)·63 citations
02
[Submitted on 13 Nov 2019]
Uncertainty quantification of an empirical shell-model interaction using principal component analysis
Jordan M. R. Fox🇺🇸 · Calvin W. Johnson🇺🇸 · Rodrigo Navarro Perez🇺🇸
Recent investigations have emphasized the importance of uncertainty quantification (UQ) to describe errors in nuclear theory. We carry out UQ for configuration-interaction shell model calculations in the $1 s$ - $0 d$ valence space, investigating the sensitivity of observables to perturbations in the 66 parameters (matrix elements) of a high-quality empirical interaction. The large parameter space makes computing the corresponding Hessian numerically costly, so we compare a cost-effective approximation, using the Feynman-Hellmann theorem, to the full Hessian and find it works well. Diagonalizing the Hessian yields the principal components of the interaction: linear combinations of parameters ordered by sensitivity. This approximately decoupled distribution of parameters facilitates theoretical error propagation onto structure observables: electromagnetic transitions, Gamow-Teller decays, and dark matter-nucleus scattering matrix elements.
Comments:
30 pages, 11 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph); Data Analysis, Statistics and Probability (physics.data-an)
arXiv:
1911.05208 [pdf]
PRC(2020)·22 citations
03
[Submitted on 13 Nov 2019]
A generalized seniority approach to the prediction of spectroscopic factors in odd-mass Sn isotopes
Bhoomika Maheshwari · Hasan Abu Kassim · Norhasliza Yusof · Ashok Kumar Jain · R. F. Casten
We present a study of the spectroscopic factors for the (d,p) stripping reactions to the $11/2^{-}$ states in the chain of odd-mass Sn (A = 115 - 131) isotopes by using a multi-j generalized seniority approach. The results are in line with realistic shell model calculations and explain the experimental trend quite well. The multi-j configuration used in these calculations is consistent with earlier calculations for moments etc., and therefore, lends credence to the generalized seniority interpretation. To the best of our knowledge, this work presents the first calculation of spectroscopic factors from such an approach.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1911.05310 [pdf]
0 citations
04
[Submitted on 13 Nov 2019]
Extracting Skyrme energy density functional parameters with Heavy-Ion Collision Data
Yingxun Zhang · Zhuxia Li · Min Liu
The effective Skyrme energy density functionals are widely used in the study of nuclear structure, nuclear reaction and neutron star, but they are less established from the heavy ion collision data. In this work, we find 22 effective Skyrme parameter sets, when incorporated in use the transport model, ImQMD, to describe the heavy ion collision data, such as isospin diffusion data at 35 MeV/u and 50 MeV/u. We use these sets to calculate the neutron skin of $^{208}$ Pb based on the restricted density variation method, and obtain the neutron skin of $^{208}$ Pb in the range of $δ R_{n p} = 0.18 \pm 0.04$ fm.
Comments:
6 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1911.05380 [pdf]
0 citations
05
[Submitted on 13 Nov 2019]
$g$ -matrix folding-model approach to reaction cross sections for scattering of Ca isotopes on a C target
Shingo Tagami · Masaomi Tanaka · Maya Takechi · Mitsunori Fukuda · Masanobu Yahiro
We first predict the ground-state properties of Ca isotopes, using the Gogny-D1S Hartree-Fock-Bogoliubov (GHFB) with and without the angular momentum projection (AMP). We find that $^{64}$ Ca is an even-dripline nucleus and $^{59}$ Ca is an odd-dripline nucleus, using $A$ dependence of the one-neutron separation energy $S_{1}$ and the two-neutron separation energy, $S_{2}$ . As for $S_{1}$ , $S_{2}$ and the binding energies $E_{B}$ , our results agree with the experimental data in $^{40 - 58}$ Ca. As other ground-state properties of $^{40 - 60, 62, 64}$ Ca, we predict charge, proton, neutron, matter radii, neutron skin and deformation. As for charge radii, our results are consistent with the experimental data in $^{40 - 52}$ Ca. For $^{48}$ Ca, our results on proton, neutron, matter radii agree with the experimental data. Very lately, Tanaka et. al. measured interaction cross sections for $^{42 - 51}$ Ca scattering on a $^{12}$ C target at an incident energy per nucleon of $E_{lab} = 280$ MeV. Secondly, we predict reaction cross sections $σ_{R}$ for $^{40 - 60, 62, 64}$ Ca, using a chiral $g$ -matrix double-folding model (DFM). To show the reliability of the present DFM for $σ_{R}$ , we apply the DFM for the data on $^{12}$ C scattering on $^{9}$ Be, $^{12}$ C, $^{27}$ Al targets in $30 < E_{lab} < 400$ MeV, and show that the present DFM is good in $30 < E_{lab} < 100$ MeV and $250 < E_{lab} < 400$ MeV. For $110 < E_{lab} < 240$ MeV, our results have small errors. To improve the present DFM for $σ_{R}$ , we propose two prescriptions.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1911.05417 [pdf]
PRC(2020)·25 citations
06
[Submitted on 12 Nov 2019]
Analytical solution of magneto-hydrodynamics with acceleration effects of Bjorken expansion in heavy-ion collisions
A. F. Kord🇮🇷 · A. Ghaani🇮🇷 · M. Haddadi Moghaddam🇮🇹
In this work, we study the 1+1 longitudinal acceleration expansion of hot and dense quark matter as a conducting relativistic fluid with the electric conductivity $σ$ . The plasma has embedded in the presence of electric and magnetic fields which are perpendicular together in the transverse plane. In order to be more realistic, we generalize the Bjorken solution, which includes the acceleration effects on the fluid expansion. We apply a perturbation fashion in initial condition to solve the relativistic magneto-hydrodynamics equations. This procedure leads us to achieve the exact algebraic expressions for both electric and magnetic fields. We also find the effects of the electromagnetic fields on the acceleration of the fluid, and the correction of energy density obtained from the magneto-hydrodynamics solutions.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
1911.05455 [pdf]
Eur.Phys.J.Plus(2022)·2 citations
07
[Submitted on 13 Nov 2019]
Energy density functional and sensitivity of energies of giant resonances to bulk nuclear matter properties
S. Shlomo · A.I. Sanzhur
The development of a modern and more realistic nuclear energy density functional (EDF) for accurate predictions of properties of nuclei is the subject of enhanced activity, since it is very important for the study of properties of nuclear matter (NM), giant resonances and, in particular, of properties of rare nuclei with unusual neutron-to-proton ratios. Here, we provide a short review of the current status of the nuclear EDF and the theoretical results obtained for properties of nuclei and nuclear matter. We will first describe a method for determining the parameters of the EDF, associated with the Skyrme type effective interaction, by carrying out a Hartree-Fock based fit to extensive set of data of ground state properties and constraints. We will then describe the fully self-consistent Hartree-Fock based random-phase-approximation theory for calculating the strength functions S(E) and centroid energies E_CEN of giant resonances and provide results for E_CEN of isoscalar and isovector giant resonances of multipolarities L=0-3 for a wide range of spherical nuclei, using 33 EDFs associated with standard form of the Skyrme type interactions, commonly employed in the literature. We investigate the sensitivities E_CEN of the giant resonances to bulk properties of NM and determine constraints on NM properties, such as the incompressibility coefficient and effective mass, by comparing with experimental data on E_CEN of giant resonances.
Comments:
Based on the talk presented at annual conference of Institute for Nuclear Research held in Kyiv, Ukraine (April, 8-12, 2019)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1911.05536 [pdf]
Nucl.Phys.Atom.Energy(2020)·0 citations
08
[Submitted on 13 Nov 2019]
Lambda-nucleon scattering in baryon chiral perturbation theory
X.-L. Ren🇩🇪 · E. Epelbaum🇩🇪 · J. Gegelia🇩🇪
We calculate the lambda-nucleon scattering phase shifts and mixing angles by applying time-ordered perturbation theory to the manifestly Lorentz-invariant formulation of SU(3) baryon chiral perturbation theory. Scattering amplitudes are obtained by solving the corresponding coupled-channel integral equations that have a milder ultraviolet behavior compared to their non-relativistic analogs. This allows us to consider the removed cutoff limit in our leading-order calculations also in the $^{3} P_{0}$ and $^{3} P_{1}$ partial waves. We find that, in the framework we are using, at least some part of the higher-order contributions to the baryon-baryon potential in these channels needs to be treated nonperturbatively and demonstrate how this can be achieved in a way consistent with quantum field theoretical renormalization for the leading contact interactions. We compare our results with the ones of the non-relativistic approach and lattice QCD phase shifts obtained for non-physical pion masses.
Comments:
13 pages, 5 figures, 3 tables. arXiv admin note: text overlap with arXiv:1905.02116
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1911.05616 [pdf]
PRC(2020)·28 citations

Affiliations

first authorsco-authorsvia INSPIRE