Nuclear Theory·nucl-th

Tuesday·August 8, 2017

13 papers—8 primary·5 cross-listed

01
[Submitted on 6 Aug 2017]
Finite-size effects on the hadron-quark phase transition in neutron stars
Xuhao Wu🇨🇳 · Hong Shen🇨🇳
We study the finite-size effects, like the surface and Coulomb energies, on the hadron-quark mixed phase in neutron stars. The equilibrium conditions for coexisting hadronic and quark phases are derived by minimizing the total energy including the surface and Coulomb contributions, which are different from the Gibbs conditions without finite-size effects. We employ the relativistic mean-field model to describe the hadronic phase, while the Nambu-Jona-Lasinio model with vector interactions is used for the quark phase. It is found that finite-size effects can significantly reduce the region of the mixed phase, and the results lie between those of the Gibbs and Maxwell constructions. We show that a massive star may contain a mixed-phase core and its size depends on the surface tension of the hadron-quark interface and the vector coupling between quarks. The repulsive vector interaction in the Nambu-Jona-Lasinio model can stiffen the equation of state of quark matter, and therefore, delay the phase transition and increase the maximum mass of neutron stars.
Comments:
22 pages, 15 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1708.01878 [pdf]
PRC(2017)·47 citations
02
[Submitted on 6 Aug 2017]
Phase shift formulas for baryon-baryon scattering in elongated boxes
Ning Li🇨🇳 · Ya-Jie Wu🇨🇳 · Zhan-Wei Liu🇨🇳
We have established the relations between the baryon-baryon scattering phase shifts and the two-particle energy spectrum in the elongated box. We have studied the cases with both the periodic boundary condition and twisted boundary condition in the center of mass frame. The framework is also extended to the system of nonzero total momentum with periodic boundary condition in the moving frame. This will be helpful to extract the phase shifts in the continuum from lattice QCD data using asymmetric volumes.
Comments:
13 pages
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1708.01879 [pdf]
0 citations
03
[Submitted on 6 Aug 2017]
{\alpha}-decay half-lives for Pb isotopes within Gamow-like model
Dashty T. Akrawy
We studed alpha decay half-lives of Pb isotopes in the range 178 < A > 220, whithin Gamow-like model (GLM) which is based on Gamow theory. The empirical formulae like Royer formula, Universal Decay Low (UDL), Viola-Seaborg formula (VSS), Semi-empirical formula for Poenaru (SemFIS) and Denisov-Khudenko formula (DEKH) are used to calculate alpha decay half-lives. The results are compared with experimental data, and also with other theoretical models, the results are in a good agreement was achieved with experimental data.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1708.01935 [pdf]
0 citations
04
[Submitted on 7 Aug 2017]
The anatomy of atomic nuclei: illuminating many-body wave functions through group-theoretical decomposition
Calvin W. Johnson
With modern computers we can compute nuclear many-body wave functions with an astounding number of component, $> 1 0^{10}$ . But, aside from reproducing and/or predicting experiments, what do we learn from vectors with tens of billions of components? One way to characterize wavefunctions is through irreducible representations of groups. I discuss briefly the history of group-theoretical characterization of nuclear wavefunctions, with an emphasis of using Lanczos-type methods to efficiently dissect arbitrary wavefunctions into group irreps. Although the resulting decompositions are often fragmented over many irreps, one nonetheless finds powerful patterns. First, group decompositions along rotational bands show coherent commonalities, supporting the picture of a shared "intrinsic shape;" this is also called \textit{quasi-dynamical symmetry}. Second, group decompositions for wave functions using both phenomenological and \textit{ab initio} forces are often very similar, despite vastly different origins and dimensionalities. Both of these results suggest a group theoretical decomposition can provide a robust "anatomy" of many nuclear wave functions. This in turn supports the idea of using symmetry-based many-body frameworks for calculations.
Comments:
8 figures, 1 table. To appear in "Emergent Phenomena in Atomic Nuclei from Large-Scale Modeling: A Symmetry-Guided Perspective," K. D. Launey, ed., World Scientific Sept 2017
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1708.01952 [pdf]
0 citations
05
[Submitted on 7 Aug 2017]
Transfer probabilities for the reactions $^{14, 20}$ O+ $^{20}$ O in terms of multiple time-dependent Hartree-Fock-Bogoliubov trajectories
Guillaume Scamps · Yukio Hashimoto
The transfer reaction between two nuclei in the superfluid phase is studied with the Time-dependent Hartree-Fock-Bogoliubov (TDHFB) theory. In order to restore the symmetry of the relative gauge angle a set of independent TDHFB evolutions is done. Then the transfer probability is computed using a triple projection method. This method is first tested to determine the transfer probabilities on a toy model and compared to the exact solution. It is then applied to the reactions $^{20}$ O+ $^{20}$ O and $^{14}$ O+ $^{20}$ O in a realistic framework with a Gogny interaction.
Comments:
6 figures, 6 pages
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1708.01994 [pdf]
PRC(2017)·25 citations
06
[Submitted on 7 Aug 2017]
Excitation energy spectra of the Lambda_c and Lambda_b baryons in a finite-size diquark model
Kento Kumakawa🇯🇵 · Daisuke Jido (Tokyo Metropolitan University)🇯🇵
The excitation energies of the $Λ_{c}$ and $Λ_{b}$ baryons are investigated in a finite-size diquark potential model, in which the heavy baryons are treated as bound states of a charm quark and a scalar-isoscalar diquark. The diquark is considered as a sizable object. The quark-diquark interaction is calculated as a sum of the quark-quark interaction which is assumed to be half of the quark-antiquark interaction for the color singlet. The potential parameters in the quark-antiquark interaction are fixed so as to reproduce the charmonium spectrum. We find the diquark size to be 1.1 fm for the diquark mass 0.5 GeV/c $^{2}$ to reproduce the $1 p$ excitation energy of $Λ_{c}$ . In this model, the $Λ_{c}$ and $Λ_{b}$ excitation spectra are reproduced well, while this model does not explain $Λ_{c} (2765)$ , whose isospin nor spin-parity are unknown yet. Thus, the detailed properties of $Λ_{c} (2765)$ is very important to the presence of the diquark in heavy baryons as a effective constituent. We also discuss the $Ξ_{c}$ spectrum with the scalar strange diquark.
Comments:
17 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1708.02012 [pdf]
PTEP(2017)·16 citations
07
[Submitted on 7 Aug 2017]
Nuclear matter fourth-order symmetry energy in non-relativistic mean-field models
Jie Pu · Zhen Zhang · Lie-Wen Chen
Based on systematic analyses of several popular non-relativistic energy density functionals with mean-field approximation, we estimate the value of the fourth-order symmetry energy $E_{sym,4} (ρ)$ at nuclear normal density $ρ_{0}$ and its density dependence, and explore the correlation between $E_{sym,4} (ρ_{0})$ and other macroscopic quantities of nuclear matter properties. We use the empirical values of some nuclear macroscopic quantities to construct model parameter sets by Monte Carlo method for the conventional Skyrme-Hartree-Fock (SHF) model, the extended Skyrme-Hartree-Fock (eSHF) model, the Gogny-Hartree-Fock (GHF) model, and the momentum-dependent interaction (MDI) model. The value of $E_{sym,4} (ρ_{0})$ is estimated to be $1.02 \pm 0.49$ MeV for the SHF model, $1.02 \pm 0.50$ MeV for the eSHF model, $0.70 \pm 0.60$ MeV for the GHF model, and $0.74 \pm 0.63$ MeV for the MDI model. Moreover, our results indicate that the density dependence of $E_{sym,4} (ρ)$ is model dependent, especially at higher densities. Furthermore, we find that the $E_{sym, 4} (ρ_{0})$ has strong positive (negative) correlation with isoscalar (isovector) nucleon effective mass $m_{s, 0}^{*}$ ( $m_{v, 0}^{*}$ ) at $ρ_{0}$ . In particular, for the SHF and eSHF models, the $E_{sym,4} (ρ)$ is completely determined by the isoscalar and isovector nucleon effective masses $m_{s}^{*} (ρ)$ and $m_{v}^{*} (ρ)$ , and the analytical expression is given. In the mean-field models, the magnitude of $E_{sym,4} (ρ_{0})$ is generally less than $2$ MeV, and its density dependence depends on models, especially at higher densities. $E_{sym,4} (ρ_{0})$ is strongly correlated with $m_{s, 0}^{*}$ and $m_{v, 0}^{*}$ .
Comments:
10 pages, 2 figures, 4 tables. Presentation improved and discussions added. Accepted version to appear in PRC
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
arXiv:
1708.02132 [pdf]
PRC(2017)·30 citations
08
[Submitted on 7 Aug 2017]
On the Connection Between the Charged and Neutral Pion-Nucleon Coupling Constants in the Yukawa Model
V. A. Babenko🇺🇦 · N. M. Petrov🇺🇦
In the Yukawa model for nuclear forces, a simple relation between the charged and neutral pion-nucleon coupling constants is derived. The relation implies that the charged pion-nucleon coupling constant is larger than the neutral one since the np interaction is stronger than the pp interaction. The derived value of the charged pion-nucleon constant shows a very good agreement with one of the recent experimental values. The relative splitting between the charged and neutral pion-nucleon coupling constants is predicted to be practically the same as that between the charged and neutral pion masses. The charge dependence of the NN scattering length arising from the mass difference between the charged and neutral pions is also analyzed.
Comments:
19 pages. Slightly modified and typos corrected version of the article published in PEPAN Letters
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1708.02198 [pdf]
Phys.Part.Nucl.Lett.(2017)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE