Nuclear Theory·nucl-th

Friday·February 11, 2022

16 papers—7 primary·9 cross-listed

01
[Submitted on 9 Feb 2022]
Tensor force effect on the neutron shell closure in super-heavy elements
M. El Adri🇲🇦 · M. Oulne🇲🇦
A systematic study of the effect of tensor force on the evolution of shell structure in even-even super-heavy nuclei in the region of proton numbers Z=114, 120 and 126 and in the region of neutron numbers 178 $\leq$ N $\leq$ 188 is presented. We use, in this investigation, the Hartree-Fock framework by means of different types of Skyrme functionals in two cases with and without tensor force. The Bardeen-Cooper-Schriefer (BCS) approximation has been used to treat the pairing correlations. By investigating structural and decay properties of nuclei under consideration, it is found that N=184 shell gap is more enhanced by the tensor interaction which depends on the isoscalar tensor coupling constant $C_{0}^{J}$ of the used Skyrme interactions. In the case without tensor interaction, this gap is significant only for T22, T24, T42 and SLy5. So, it disappears with T46, T64 and T66, and is too weak for T26, T44 and T62. Without exception, the shell gap at N=184 becomes more pronounced when the tensor part is taken into account.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2202.04691 [pdf]
Eur.Phys.J.Plus(2021)·1 citation
02
[Submitted on 9 Feb 2022]
On the possible existence of a soft dipole mode in 8He
J. Piekarewicz
With an extreme neutron-to-proton ratio of N/Z=3, 8He provides an ideal laboratory for the study of a variety of exotic phenomena, such as the emergence of a soft dipole mode that is dominated by transitions into the continuum. In this contribution, a covariant density functional theory (DFT) framework is used to compute ground-state properties and the dipole response of 8He. Although 8He is admittedly too light for DFT to be applicable, the great merit of the approach is that the spurious contamination associated with the center-of-mass motion is guaranteed to decouple from the physical response. Given that a strong mixing between the isoscalar and isovector dipole modes is expected for a system with such a large neutron-proton asymmetry as 8He, the narrow structures that emerged at low energies in the isovector dipole response are attributed to the shift of the spurious strength to zero (or near zero) excitation energy. Thus, the theoretical framework implemented here disfavors the emergence of a soft dipole mode in 8He.
Comments:
8 pages, 7 figures, and two tables. Submitted to the Physical Review C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2202.04726 [pdf]
PRC(2022)·6 citations
03
[Submitted on 9 Feb 2022]
Weak pion-production and the second resonance region
D.F. Tamayo Agudelo🇨🇴 · A. Mariano🇦🇷 · D.E. Jaramillo Arango🇨🇴
In this work we report the calculation of the total cross section for pion-production by the dispersion of neutrinos on nucleons. We use a consistent formalism for the intermediate resonance states of spin $3/2$ , taking care on the conditions imposed by the invariance on contact transformations and using the Sachs parametrization for the form factors. In addition, we incorporate states in the second resonance region up to 1.6 GeV and implement different approaches for all the dressed resonance propagators. In addition to the $Δ$ (1232), we include the N $^{*}$ (1440),N $^{*}$ (1535)and N $^{*}$ (1520) resonance contributions, and it is shown that this inclusion improve the description of the total cross section regards a model where only the $Δ$ (1230) resonance is considered. Also results for antineutrinos are properly described.
Comments:
Manuscript has been accepted for publication as a Regular Article in Physical Review D
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2202.04760 [pdf]
PRD(2022)·3 citations
04
[Submitted on 10 Feb 2022]
Chiral condensates for neutron stars in hadron-quark crossover; from a parity doublet nucleon model to an NJL quark model
Takuya Minamikawa🇯🇵 · Toru Kojo🇨🇳 · Masayasu Harada🇯🇵
In this contribution, we summarize our recent studies on the chiral invariant mass and the chiral condensates in neutron star matter. We construct a unified equations of state assuming the crossover phase transition from hadronic matter described by a parity doublet model to quark matter by an Nambu--Jona-Lasinio type quark model. We first show that the chiral invariant mass is constrained to be 600 MeV $≲ m_{0} ≲$ 900 MeV from recent observations of neutron stars. We then determine the density dependence of the chiral condensate in the crossover description, and show that the chiral condensates are actually smoothly connected from the hadronic matter where the change is driven by the positive chiral scalar charge in a nucleon, to the quark matter where the change is by the modification of the quark Dirac sea, reflecting the hadron-quark crossover.
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2202.04873 [pdf]
Rev.Mex.Fis.Suppl.(2022)·2 citations
05
[Submitted on 10 Feb 2022]
Isospin symmetry breaking in the charge radius difference of mirror nuclei
Tomoya Naito · Xavier Roca-Maza · Gianluca Colò · Haozhao Liang · Hiroyuki Sagawa
Isospin symmetry breaking (ISB) effects in the charge radius difference $Δ R_{ch}$ of mirror nuclei are studied using the test example of $^{48}$ Ca and $^{48}$ Ni. This choice allows for a transparent study of ISB contributions since paring and deformation effects, commonly required for the study of mirror nuclei, can be neglected in this specific pair. The connection of $Δ R_{ch}$ with the nuclear Equation of State and the effect of ISB on such a relation are discussed according to an Energy Density Functional approach. We find that nuclear ISB effects may shift the estimated value for the symmetry energy slope parameter $L$ by more than 10 MeV while Coulomb corrections can be neglected. ISB effects on the ground-state energy and charge radii in mirror nuclei have been recently predicted by {\it ab initio} calculations to be relatively small, pointing to a negligible effect for the extraction of information on the nuclear EoS. These contrasting results call for a dedicated theoretical effort to solve this overarching problem that impacts not only the neutron skin thickness or the difference in mass and charge radii of mirror nuclei but also other observables such as the Isobaric Analog State energy.
Comments:
Submitted for publication
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2202.05035 [pdf]
PRC(2022)·26 citations
06
[Submitted on 10 Feb 2022]
Quark deconfinement in compact stars through sexaquark condensation
D. Blaschke🇵🇱 · O. Ivanytskyi🇵🇱 · M. Shahrbaf🇵🇱
In this contribution, we present for the first time a scenario according to which early quark deconfinement in compact stars is triggered by the Bose-Einstein condensation (BEC) of a light sexaquark (S) with a mass $m_{S} < 2054$ MeV, that has been suggested as a candidate particle to explain the baryonic dark matter in the Universe. The onset of S BEC marks the maximum mass of hadronic neutron stars and it occurs when the condition for the baryon chemical potential $μ_{b} = m_{S} /2$ is fulfilled in the center of the star, corresponding to $M_{onset} ≲ 0.7 M_{⊙}$ . In the gravitational field of the star the density of the BEC of the S increases until a new state of the matter is attained, where each of the S-states got dissociated into a triplet of color-flavor-locked (CFL) diquark states. These diquarks are the Cooper pairs in the color superconducting CFL phase of quark matter, so that the developed scenario corresponds to a BEC-BCS transition in strongly interacting matter. For the description of the CFL phase, we develop here for the first time the three-flavor extension of the density-functional formulation of a chirally symmetric Lagrangian model of quark matter where confining properties are encoded in a divergence of the scalar self-energy at low densities and temperatures.
Comments:
27 pages, 8 figures, Contribution to the Book "New Phenomena and New States of Matter in the Universe. From Quarks to Cosmos" edited by C. A. Z. Vasconcellos, P. O. Hess and T. Boller
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2202.05061 [pdf]
New Phenomena and New States of Matter in…·10 citations
07
[Submitted on 10 Feb 2022]
Landau parameters and entrainment matrix of cold stellar matter: effect of the symmetry energy and strong magnetic fields
Helena Pais · Oleksii Ivanytskyi · Constança Providência
Nuclear matter properties based on a relativistic approach suitable for the description of multi-component systems are calculated. We use a set of nuclear relativistic mean-field models that satisfy acceptable nuclear matter properties and neutron star observations. The effects of the density dependence of the symmetry energy and of the Landau quantization due to the presence of a strong external magnetic field are discussed. Properties such as the proton fraction, the Landau mass, Landau parameters and entrainment matrix, the adiabatic index and speed of sound are calculated for cold $β$ -equilibrium matter. A large dispersion on the calculated properties is obtained at two to three times saturation density $ρ_{0}$ . The proton Landau mass can be as low as one third of the vacuum nucleon mass at 2-3 $ρ_{0}$ . Similar effects are obtained for the Landau parameters, in particular, the ones involving protons, where the relative dispersion of $F_{pp}^{0}$ and $F_{pp}^{1}$ is as high as 30\% to 50\% at 2-3 $ρ_{0}$ . These parameters are particularly sensitive to the symmetry energy. The effect of the magnetic field on the nuclear properties is small for fields as high as 10 $^{18}$ G except for a small range of densities just above the crust-core transition. Tables with the EoS, and the parameters, are provided in the Supplementary Material section.
Comments:
26 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2202.05231 [pdf]
JCAP(2022)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Tensor force effect on the neutron shell closure in super-heavy elements

On the possible existence of a soft dipole mode in 8He

Weak pion-production and the second resonance region

Chiral condensates for neutron stars in hadron-quark crossover; from a parity doublet nucleon model to an NJL quark model

Isospin symmetry breaking in the charge radius difference of mirror nuclei

Quark deconfinement in compact stars through sexaquark condensation

Landau parameters and entrainment matrix of cold stellar matter: effect of the symmetry energy and strong magnetic fields

Affiliations