Nuclear Theory·nucl-th

Friday·January 22, 2021

7 papers—4 primary·3 cross-listed

01
[Submitted on 21 Jan 2021]
Giant dipole resonance in Sm isotopes within TDHF method
Ait Ben Mennana Azzeddine🇲🇦 · Mostafa Oulne🇲🇦
In this work, we have studied the isovector giant dipole resonance (IVGDR) in even-even Sm isotopes within time-dependent Hartree-Fock (TDHF) with four Skyrme forces SLy6, SVbas, SLy5 and UNEDF1. The approach we have followed is somewhat similar to the one we did in our previous work in the region of Neodymium (Nd, Z=60) [\href{https://iopscience.iop.org/article/10.1088/1402-4896/ab73d8}{Physica Scripta (2020)}]. We have calculated the dipole strength of $^{128 - 164} Sm$ , and compared with the available experimental data. An overall agreement between them is obtained. The dipole strength in neutron-deficient $^{128 - 142} Sm$ and in neutron-rich $^{156 - 164} Sm$ isotopes are predicted. Shape phase transition as well as shape coexistence in Sm isotopes are also investigated in the light of IVGDR. In addition, the correlation between the quadrupole deformation parameter $β_{2}$ and the splitting $Δ E / E ˉ_{m}$ of the giant dipole resonance (GDR) spectra is studied. The results confirm that $Δ E / E ˉ_{m}$ is proportional to quadrupole deformation $β_{2}$
Comments:
17 pages, 22 figures. arXiv admin note: text overlap with arXiv:2005.04337
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2101.08400 [pdf]
Eur.Phys.J.Plus(2021)·9 citations
02
[Submitted on 21 Jan 2021]
Momentum dependent mean-fields of (anti)hyperons
T. Gaitanos🇬🇷 · A. Chorozidou🇬🇷
We investigate the in-medium properties of hyperons and anti-hyperons in the framework of the Non-Linear Derivative (NLD) model. We focus on the momentum dependence of in-medium strangeness optical potentials. The NLD model is based on the simplicity of the well-established Relativistic Mean-Field (RMF) approximation, but it incorporates an explicit momentum dependence on a field-theoretical level. The extension of the NLD model to the (anti)baryon-octet is formulated in the spirit of SU(6) and G-parity arguments. It is shown that with an appropriate choice of momentum cut-offs the $Λ$ , $Σ$ and $Ξ$ optical potentials are consistent with recent studies of the chiral effective field theory and Lattice-QCD calculations over a wide momentum region. In addition, we present NLD predictions for the in-medium momentum dependence of $Λ$ -, $Σ$ - and $Ξ$ -hyperons. This work is important for future experimental studies such as CBM, PANDA at the Facility for Antiproton and Ion Research (FAIR). It is relevant for nuclear astrophysics too.
Comments:
18 pages, 8 figures, accepted for publication in Nuclear Physics A
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2101.08470 [pdf]
NPA(2021)·16 citations
03
[Submitted on 21 Jan 2021]
Electric dipole polarizability in neutron-rich Sn isotopes as a probe of nuclear isovector properties
Zhengzheng Li · Yifei Niu · Wenhui Long
The determination of nuclear symmetry energy, and in particular, its density dependence, is a long-standing problem for nuclear physics community. Previous studies have found that the product of electric dipole polarizability $α_{D}$ and symmetry energy at saturation density $J$ has a strong linear correlation with $L$ , the slope parameter of symmetry energy. However, current uncertainty of $J$ hinders the precise constraint on $L$ . We investigate the correlations between electric dipole polarizability $α_{D}$ (or times symmetry energy at saturation density $J$ ) in Sn isotopes and the slope parameter of symmetry energy $L$ using the quasiparticle random-phase approximation based on Skyrme Hartree-Fock-Bogoliubov. A strong and model-independent linear correlation between $α_{D}$ and $L$ is found in neutron-rich Sn isotopes where pygmy dipole resonance (PDR) gives a considerable contribution to $α_{D}$ , attributed to the pairing correlations playing important roles through PDR. This newly discovered linear correlation would help one to constrain $L$ and neutron-skin thickness $Δ R_{np}$ stiffly if $α_{D}$ is measured with high resolution in neutron-rich nuclei. Besides, a linear correlation between $α_{D} J$ in a nucleus around $β$ -stability line and $α_{D}$ in a neutron-rich nucleus can be used to assess $α_{D}$ in neutron-rich nuclei.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2101.08528 [pdf]
PRC(2021)·20 citations
04
[Submitted on 21 Jan 2021]
In-medium $Δ (1232)$ potential, pion production in heavy-ion collisions and the symmetry energy
M.D. Cozma🇺🇸 · M.B.Tsang🇺🇸
Using the dcQMD transport model, the isoscalar and isovector in-medium potentials of the $Δ$ (1232) baryon are studied and information regarding their effective strength is obtained from a comparison to experimental pion production data in heavy-ion collisions below 800 MeV/nucleon impact energy. The best description is achieved for an isoscalar potential moderately more attractive than the nucleon optical potential and a rather small isoscalar relative effective mass m $_{Δ}^{*} \approx$ 0.45. For the isovector component only a constraint between the potential's strength at saturation and the isovector effective mass difference can be extracted, which depends on quantities such as the slope of the symmetry energy and the neutron-proton effective mass difference. These results are incompatible with the usual assumption, in transport models, that the $Δ$ (1232) and nucleon potentials are equal. The density dependence of symmetry energy can be studied using the high transverse momentum tail of pion multiplicity ratio spectra. Results are however correlated with the value of neutron-proton effective mass difference. This region of spectra is shown to be affected by uncertain model ingredients such as the pion potential or in-medium correction to inelastic scattering cross-sections at levels smaller than 10 $%$ . Extraction of precise constraints for the density dependence of symmetry energy above saturation will require experimental data for pion production in heavy-ion collisions below 800 MeV/nucleon impact energy and experimental values for the high transverse momentum tail of pion multiplicity ratio spectra accurate to better than 5 $%$ .
Comments:
22 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2101.08679 [pdf]
EPJA(2021)·34 citations

Affiliations

first authorsco-authorsvia INSPIRE

Giant dipole resonance in Sm isotopes within TDHF method

Momentum dependent mean-fields of (anti)hyperons

Electric dipole polarizability in neutron-rich Sn isotopes as a probe of nuclear isovector properties

In-medium Δ(1232) potential, pion production in heavy-ion collisions and the symmetry energy

Affiliations

In-medium $Δ (1232)$ potential, pion production in heavy-ion collisions and the symmetry energy