Nuclear Theory·nucl-th

Wednesday·June 9, 2021

15 papers—8 primary·7 cross-listed

01
[Submitted on 8 Jun 2021]
Evolution of octupole deformation and collectivity in neutron-rich lanthanides
K. Nomura · R. Rodríguez-Guzmán · L. M. Robledo · J. E. García-Ramos · N. C. Hernández
The onset of octupole deformation and its impact on related spectroscopic properties is studied in even-even neutron-rich lanthanide isotopes Xe, Ba, Ce, and Nd with neutron number $86 ⩽ N ⩽ 94$ . Microscopic input comes from the Hartree-Fock-Bogoliubov approximation with constrains on the axially symmetric quadrupole and octupole operators using the Gogny-D1M interaction. At the mean-field level, reflection asymmetric ground states are predicted for isotopes with neutron number around $N = 88$ . Spectroscopic properties are studied by diagonalizing the interacting boson model Hamiltonian, with the parameters obtained via the mapping of the mean-field potential energy surface onto the expectation value of the Hamiltonian in the $s$ , $d$ , and $f$ boson condensate state. The results obtained for low-energy positive- and negative-parity excitation spectra as well as the electric dipole, quadrupole, and octupole transition probabilities indicate the onset of pronounced octupolarity for $Z \approx 56$ and $N \approx 88$ nuclei.
Comments:
15 pages, 13 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2106.04076 [pdf]
PRC(2021)·34 citations
02
[Submitted on 8 Jun 2021]
Revisiting the variational two-particle reduced density matrix for nuclear systems
J. G. Li · N. Michel · W. Zuo · F. R.Xu
In most nuclear many-body methods, observables are calculated using many-body wave functions explicitly. The variational two-particle reduced density matrix method is one of the few exceptions to the rule. Ground-state energies of both closed-shell and open-shell nuclear systems can indeed be evaluated by minimizing a constrained linear functional of the two-particle reduced density matrix. However, it has virtually never been used in nuclear theory, because nuclear ground states were found to be well overbound, contrary to those of atoms and molecules. Consequently, we introduced new constraints in the nuclear variational two-particle reduced density matrix method, developed recently for atomic and molecular systems. Our calculations then show that this approach can provide a proper description of nuclear systems where only valence neutrons are included. For the nuclear systems where both neutrons and protons are active, however, the energies obtained with the variational two-particle reduced density matrix method are still overbound. The possible reasons for the noticed discrepancies and solutions to this problem will be discussed.
Comments:
14 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph); physics.chem-ph (physics.chem-ph)
arXiv:
2106.04103 [pdf]
PRC(2021)·1 citation
03
[Submitted on 8 Jun 2021]
Constraints on the phase transition and nuclear symmetry parameters from PSR $J 0740 + 6620$ and multimessenger data of other neutron stars
Shao-Peng Tang🇨🇳 · Jin-Liang Jiang🇨🇳 · Ming-Zhe Han🇨🇳 · Yi-Zhong Fan🇨🇳 · Da-Ming Wei🇨🇳
Recently, the radius of neutron star (NS) PSR J0740+6620 was measured by Neutron Star Interior Composition Explorer (NICER) and an updated measurement of neutron skin thickness of $^{208}$ Pb ( $R_{skin}^{208}$ ) was reported by the PREX-II experiment. These new measurements can help us better understand the unknown equation of state (EOS) of dense matter. In this work, we adopt a hybrid parameterization method, which incorporates the nuclear empirical parameterization and some widely used phenomenological parameterizations, to analyze the results of nuclear experiments and astrophysical observations. With the joint Bayesian analysis of GW170817, PSR J0030+0451, and PSR J0740+6620, the parameters that characterize the ultradense matter EOS are constrained. We find that the slope parameter $L$ is approximately constrained to $7 0_{- 18}^{+ 21}$ MeV, which predicts $R_{skin}^{208} = 0.20 4_{- 0.026}^{+ 0.030} fm$ by using the universal relation between $R_{skin}^{208}$ and $L$ . The bulk properties of canonical $1.4 M_{⊙}$ NS (e.g., $R_{1.4}$ and $Λ_{1.4}$ ) as well as the pressure ( $P_{2 ρ_{sat}}$ ) at two times the nuclear saturation density are well constrained by the data; i.e., $R_{1.4}$ , $Λ_{1.4}$ , and $P_{2 ρ_{sat}}$ are approximately constrained to $12.3 \pm 0.7$ km, $33 0_{- 100}^{+ 140}$ , and $4. 1_{- 1.2}^{+ 1.5} \times 1 0^{34} dyn c m^{- 2}$ , respectively. Besides, we find that the Bayes evidences of the hybrid star and normal NS assumptions are comparable, which indicates that current observation data are compatible with quarkyonic matter existing in the core of massive star. Finally, in the case of normal NS assumption, we obtain a constraint for the maximum mass of nonrotating NS $M_{TOV} = 2.3 0_{- 0.18}^{+ 0.30}$ $M_{⊙}$ . All of the uncertainties reported above are for 68.3% credible levels.
Comments:
12 pages, 7 figures, published in PRD
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2106.04204 [pdf]
PRD(2021)·41 citations
04
[Submitted on 8 Jun 2021]
Production cross sections of $_{Λ}^{3, 4}$ H bound states in $^{3, 4}$ He( $K^{-}$ , $π^{0}$ ) reactions at 1 GeV/ $c$
Toru Harada🇯🇵 · Yoshiharu Hirabayashi🇯🇵
We investigate theoretically productions of $_{Λ}^{3, 4}$ H bound states in the exothermic ( $K^{-}$ , $π^{0}$ ) reactions on $^{3, 4}$ He targets at $p_{K^{-}} =$ 1.0 GeV/c in a distorted-wave impulse approximation with the optimal Fermi-averaging $K^{-} p \to π^{0} Λ$ $t$ matrix. We calculate angular distributions of the laboratory differential cross sections $d σ / d Ω_{lab}$ and the integrated cross sections $σ_{lab}$ for a $J^{P} = 0^{+}$ ground state and a $J^{P} = 1^{+}$ excited state of $_{Λ}^{4}$ H at $π^{0}$ forward-direction angles of $θ_{lab} =$ 0 $^{\circ}$ -20 $^{\circ}$ , and those for a $J^{P} = 1/ 2^{+}$ ground state of $_{Λ}^{3}$ H. The production of a $J^{P} = 3/ 2^{+}$ excited state of $_{Λ}^{3}$ H as a virtual state is also evaluated. The comparison in $d σ / d Ω_{lab}$ and $σ_{lab}$ between $_{Λ}^{4}$ H and $_{Λ}^{3}$ H provides examining the mechanism of the production and structure of $_{Λ}^{3, 4}$ H, as well as in the endothermic ( $π^{-}$ , $K^{0}$ ) reactions at $p_{π^{-}} =$ 1.05 GeV/c. This investigation confirms the feasibility of lifetime measurements of $_{Λ}^{3}$ H at the J-PARC experiments.
Comments:
22 pages, 5 figures, 4 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2106.04256 [pdf]
NPA(2021)·7 citations
05
[Submitted on 8 Jun 2021]
$^{12} C +^{12} C$ Fusion $S^{*}$ -factor from a Full-microscopic Nuclear Model
Yasutaka Taniguchi · Masaaki Kimura
The $^{12} C +^{12} C$ fusion reaction plays a vital role in the explosive phenomena of the universe. The resonances in the Gamow window rule its reaction rate and products. Hence, the determination of the resonance parameters by nuclear models is indispensable as the direct measurement is not feasible. Here, for the first time, we report the resonances in the $^{12} C +^{12} C$ fusion reaction described by a full-microscopic nuclear model. The model plausibly reproduces the measured low-energy astrophysical $S$ -factors and predicts the resonances in the Gamow window. Contradictory to the hindrance model, we conclude that there is no low-energy suppression of the $S$ -factor.
Comments:
5 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2106.04321 [pdf]
PLB(2021)·30 citations
06
[Submitted on 8 Jun 2021]
Implications of PREX--2 data on the electron--neutrino opacity in dense matter
Parada T.P. Hutauruk🇰🇷
Motivated by the recent measurement of the neutron distribution radius of $^{208}$ Pb from the PREX--2 data, I study the effects of the new G3(M) parameter set constrained by PREX--2 data on the electron--neutrino scattering in dense matter using the extended relativistic mean field (E--RMF) model. I employ the G3(M) parameter set to describe the nuclear matter. The obtained equation of state for the G3(M) parameter set has an excellent agreement with experimental data and the chiral effective field theory calculation with N $^{3}$ LO 3N forces. I analyze both differential cross section of electron--neutrino and electron--neutrino mean free path to observe their sensitivity to the G3(M) parameter set. One finds that the differential cross sections of electron--neutrino for different baryon densities have higher values compared with that obtained for the TM1e and FSU Garnet parameter sets. The higher cross section decreases the electron--neutrino mean free path.
Comments:
8 pages, 7 figures, to appear in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2106.04474 [pdf]
PRC(2021)·5 citations
07
[Submitted on 8 Jun 2021]
Ground State Properties of Charmed Hypernuclei with Mean Field Approach
H. Güven🇫🇷 · K. Bozkurt🇫🇷 · E. Khan🇫🇷 · J. Margueron🇫🇷
Closed shell charmed hypernuclei $_{Λ_{c}}^{5}$ Li, $_{Λ_{c}}^{17}$ F, $_{Λ_{c}}^{41}$ Sc, $_{Λ_{c}}^{57}$ Cu, $_{Λ_{c}}^{133}$ Sb and $_{Λ_{c}}^{209}$ Bi are calculated within Hartree-Fock approach by using three different force sets derived from microscopic Brueckner-Hartree-Fock calculations of $Λ$ hypernuclei. Ground state properties (binding energies, $Λ_{c}$ separation energies, $Λ_{c}$ single particle energies and $Λ_{c}$ densities) of charmed nuclei are examined. Due to the Coulomb repulsion between protons and the $Λ_{c}$ baryon, charmed hypernuclei are most bound for $16 \leq$ A $\leq 41$ , where $_{Λ_{c}}^{17}$ F can be considered as an excellent candidate to measure charmed hypernuclei. The competition between the attractive nucleon- $Λ_{c}$ interaction and the Coulomb repulsion is discussed, and we compare $Λ$ and $Λ_{c}$ hypernuclei properties.
Comments:
9 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2106.04491 [pdf]
PRC(2021)·5 citations
08
[Submitted on 8 Jun 2021]
Hubble Expansion and Freeze-Out at RHIC-BES Energies from UrQMD
Gabriele Inghirami🇩🇪 · Tom Reichert🇩🇪 · Marcus Bleicher🇩🇪
The freeze-out process in heavy ion collisions is driven by the competition between the scattering rate and the expansion rate of the matter. We analyse the expansion rate $Θ$ (often called Hubble flow) in relativistic heavy ion collisions in the FAIR and RHIC-BES energy regimes and compare it to the scattering rate $Γ$ using the UrQMD transport model. We observe that the time evolution of the system is clearly separated into a compression phase and an expansion phase with time dependent $Θ_{∥}$ and $Θ_{⊥}$ . The calculated values of the Hubble expansion at kinetic decoupling are in line with previous simple estimates by statistical hadronization models with a Siemens-Rasmussen type emission source. However, the actual shape of the expanding matter is, as expected, found to be between a spherically symmetric and a purely longitudinal expansion. We confirm for the first time in a microscopic simulation that the decoupling hypersurface is indeed determined by the competition of the expansion rate $Θ$ and the scattering rate $Γ$ as suggested previously. This suggests that, in the range of collision energies explored in this study, simple iso-thermal/iso-energy density criteria that are often used in hybrid models to couple hydrodynamic and transport simulations may not capture the true decoupling hyper-surface.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2106.04543 [pdf]
5 citations

Affiliations

first authorsco-authorsvia INSPIRE