arXiv subjects

Xian-Rong Zhou

Publications and source records attributed to Xian-Rong Zhou.

14 recordsLinked to original sources

arXiv2025

Hypernuclear structure with the new leading order covariant chiral hyperon-nucleon force

We have studied single-$\Lambda$ finite hypernuclear systems spanning from light to heavy masses, employing a new microscopic Lambda-N interaction derived from in-medium interactions within relativistic Brueckner-Hartree-Fock calculations using the leading-order covariant chiral hyperon-nucleon force. Without any adjustable parameters, we have successfully reproduced the experimental results for the single-Lambda binding energies. Although some discrepancies persist in light hypernuclei, the overall calculated binding energies show excellent agreement with the experimental data, and outperforming other microscopic interactions. This study further demonstrates the validity of the leading-order covariant chiral hyperon-nucleon potential and provides a practical set of microscopic interactions for the Skyrme-Hartree-Fock framework.

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arXiv2025

Charge symmetry breaking effect in mirror {\Lambda} hypernuclei with Skyrme-Hartree-Fock model

We study the charge symmetry breaking (CSB) effect in mirror hypernuclei using the deformed Skyrme Hartree-Fock (DSHF)+ Bardeen-Cooper-Schrieffer (BCS) model together with the CSB term and pairing interaction. Our model provides good account for the observations of CSB effect in mirror hypernuclei in the mass region of A = 7~16. We investigate the effect of deformation on the single-Lambda binding energy differences and we found that, in mirror hypernuclei with mass numbers A = 8 and A = 9, deformation has a noticeable impact on the energy difference.

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arXiv2024

Gamow shell model description of neutron-rich He hyper-isotopes

The Gamow shell model (GSM) framework has been extended to the study of weakly bound hypernuclei. As a first application, the neutron-rich He hyper-isotope chains, from 6{\Lambda}He to 9{\Lambda}He have been investigated to accurately account for the loosely bound or neutron-unbound character of hypernuclear many-body states. The energy spectra calculated with a phenomenological Hamiltonian show good agreement with experimental data. In particular, neutron-emitting resonant states are predicted for the neutron-rich nuclei 5-7He and the hypernucleus 6{\Lambda}He. Furthermore, one-neutron densities exhibit the long-range character of weakly bound and resonant states. This study demonstrates that GSM is a practical tool for describing the complex structure of hypernuclei, especially for those close to drip lines.

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arXiv2024

Shape coexistence in Ne isotopes and hyperon impurity effect on low-lying states

Based on the beyond-mean-field Skyrme-Hartree-Fock model, we investigate the shape coexistence in Ne isotopes and the effect of $\la$ hyperon on the energy level structure in the nuclei. The up-to-date Skyrme-type $N\la$ interaction SLL4 and the $NN$ interaction SGII are employed. Low-lying energy spectra of $^{20,22,24,26,28,30,32,34}$Ne, including the low-lying states with $J\leq 6$, are predicted, discussed in detail, and found in good agreement with experimental results. The electric quadrupole transition rate is also examined. The coexistences of a ground state rotational band and a $\be$ vibrational band are revealed in $^{20,22,24}$Ne. Unlike the previously discovered shrinkage effect of $\la_{s}$ on the ground state nuclei, it is found that the $\la_{s}$ may alter the excitation mode of the second band by affecting the distribution of the collective wave function, thereby causing the $\be$ vibrational band transitions to a vibrational band with equidistant energy levels.

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arXiv2024

Proton drip line of deformed hypernuclei

The proton drip line of (hyper)nuclei is examined within the framework of the deformed Skyrme-Hartree Fock approach by adjusting the nuclear force parameters to exactly reproduce the core binding energies. The impact of adding a {\Lambda} hyperon in a s or p state is studied, and it is found that in some cases the deformation effect facilitates the extension of the drip line by an added p-state hyperon. However, no extension of the drip line is found for s-state hypernuclei.

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arXiv2021

Effects of $\bm\la$ hyperons on the deformations of even-even nuclei

The deformations of multi-$\la$ hypernuclei corresponding to even-even core nuclei ranging from $^8$Be to $^{40}$Ca with 2, 4, 6, and 8 hyperons are studied in the framework of the deformed Skyrme-Hartree-Fock approach. It is found that the deformations are reduced when adding 2 or 8 $\la$ hyperons, but enhanced when adding 4 or 6 $\la$ hyperons. These differences are attributed to the fact that $\la$ hyperons are filled gradually into the three deformed $p$ orbits, of which the [110]1/2$^-$ orbit is prolately deformed and the degenerate [101]1/2$^-$ and [101]3/2$^-$ orbits are oblately deformed.

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arXiv2021

The drip lines of kaonic nuclei

The effects of an additional $K^-$ meson on the neutron and proton drip lines are investigated within Skyrme-Hartree-Fock approach combined with a Skyrme-type kaon-nucleon interaction. While an extension of the proton drip line is observed due to the strongly attractive $K^-p$ interaction, contrasting effects (extension and reduction) on the neutron drip line of Be, O, and Ne isotopes are found. The origin of these differences is attributed to the behavior of the highest-occupied neutron single-particle levels near the neutron drip line.

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arXiv2019

Study of $\Xi^-$ hypernuclei in the Skyrme-Hartree-Fock approach

The properties of $\Xi^-$ hypernuclei are studied systematically using a two-dimensional Skyrme-Hartree-Fock approach combined with three different $\Xi N$ Skyrme forces fitted to reproduce the existing data. We explore the impurity effect of a single $\Xi^-$ hyperon on the radii, deformations, and density distributions of the nuclear core and point out qualitative differences between the different forces. We find that the $\Xi^-$ removal energy of $^{\hskip0.10em13}_{\Xi p}$B [$^{12}$C(g.s.)+ $\Xi^-$(1p)] calculated by the SLX3 force is 0.7 MeV, which is in good agreement with a possible value of $0.82\pm0.17\;$MeV from the KEK E176 experiment. The theoretical prediction for this weakly bound state depends strongly on the deformation of the nuclear core, which is analyzed in detail.

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arXiv2019

Deformed $K^-$ nuclei in the Skyrme-Hartree-Fock approach

The properties of kaonic nuclei are studied using a two-dimensional Skyrme-Hartree-Fock model with a $KN$ Skyrme force. We focus in particular on the instability of the solutions for a too strong $KN$ interaction, which determines a maximum value of the kaon binding in this approach. We then analyze the change of the deformation properties of several core-deformed nuclei caused by the added kaon, and find a shrinking of the core and in some cases a complete loss of deformation.

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arXiv2017

Beyond-mean-field study of the hyperon impurity effect in hypernuclei with shape coexistence

[Background] The hyperon impurity effect in nuclei has been extensively studied in different mean-field models. Recently, there is a controversy about whether the $\Lambda$ hyperon is more tightly bound in the normal deformed (ND) states than that in the superdeformed (SD) states.[Purpose] This article is aimed to provide a beyond-mean-field study of the low-lying states of hypernuclei with shape coexistence and to shed some light on the controversy.[Method] The models of relativistic mean-field and beyond based on a relativistic point-coupling energy functional are adopted to study the low-lying states of both $^{37}_\Lambda$Ar and $^{36}$Ar. The wavefunctions of low-lying states are constructed as a superposition of a set of relativistic mean-field states with different values of quadrupole deformation parameter. The projections onto both particle number and angular momentum are considered.[Results] The $\Lambda$ binding energies in both ND and SD states of $^{37}_{\Lambda}$Ar are studied in the case of the $\Lambda$ hyperon occupying $s, p$, or $d$ state in the spherical limit, respectively. For comparison, four sets of nucleon-hyperon point-coupling interactions are used respectively. Moreover, the spectra of low-lying states in $^{36}$Ar and $^{37}_{\Lambda_s}$Ar are calculated based on the same nuclear energy density functional. The results indicate that the SD states exist in $^{37}_{\Lambda}$Ar for all the four effective interactions. Furthermore, the $\Lambda_s$ reduces the quadrupole collectivity of ND states to a greater extent than that of SD states. For $^{37}_{\Lambda}$Ar, the beyond-mean-field decreases the $\Lambda_s$ binding energy of the SD state by 0.17 MeV, but it almost has no effect on that of the ND state. [Conclusions] In $^{37}_{\Lambda_s}$Ar, the $\Lambda_p$ and $\Lambda_d$ binding energies of the SD states ...

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arXiv2015

Global performance of multireference density functional theory for low-lying states in $sd$-shell nuclei

We present a comprehensive study of low-lying states in even-even Ne, Mg, Si, S, Ar isotopes with the multireference density functional theory (MR-DFT) based on a relativistic point-coupling energy density functional (EDF). Beyond mean-field (BMF) effects are taken into account by configuration mixing of both particle-number and angular-momentum projected axially deformed states with generator coordinate method (GCM). Global performance of the MR-DFT for the properties of both ground state and of the first $2^+, 4^+$ states is examined, in comparison with previous studies based on nonrelativistic EDFs and available data. Our results indicate that an EDF parameterized at the BMF level is demanded to achieve a quantitative description.

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arXiv2014

Description of collective and quasiparticle excitations in deformed actinide nuclei: The first application of the Heavy Shell Model

The Heavy Shell Model (HSM) (Y. Sun and C.-L. Wu, Phys. Rev. C 68, 024315 (2003)) was proposed to take the advantages of two existing models, the projected shell model (PSM) and the Fermion Dynamical Symmetry Model (FDSM). To construct HSM, one extends the PSM by adding collective D-pairs into the intrinsic basis. The HSM is expected to describe simultaneously low-lying collective and quasi-particle excitations in deformed nuclei, and still keeps the model space tractable even for the heaviest systems. As the first numerical realization of the HSM, we study systematically the band structures for some deformed actinide nuclei, with a model space including up to 4-quasiparticle and 1-D-pair configurations. The calculated energy levels for the ground- state bands, the collective bands such as β - and γ -bands, and some quasiparticle bands agree well with known experimental data. Some low-lying quasiparticle bands are predicted, awaiting experimental confirmation.

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arXiv2007

Charge Exchange Spin-Dipole Excitations of 90Zr and 208Pb and Neutron Matter Equation of State

Charge exchange spin-dipole (SD) excitations of $^{90}$Zr and $^{208}$Pb are studied by using a Skyrme Hartree-Fock(HF) + Random Phase approximation (RPA). The calculated spin-dipole strength distributions are compared with experimental data obtained by $^{90}$Zr (p,n) $^{90}$Nb and $^{90}$Zr (n,p) $^{90}$ Nb reactions. The model-independent SD sum rule values of various Skyrme interactions are studied in comparison with the experimental values in order to determine the neutron skin thickness of $^{90}$Zr. The pressure of the neutron matter equation of state (EOS) and the nuclear matter symmetry energy are discussed in terms of the neutron skin thickness and peak energies of SD strength distributions.

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arXiv2004

Nuclear structure of 178Hf related to the spin-16, 31-year isomer

The projected shell model is used to study the multi-quasiparticle and collective excitations of 178Hf. With an axially symmetric basis, the spin-16 isomer at 2.4 MeV appears to be well separated in energy/spin space from other configurations. However, projected energy surface calculations suggest that 178Hf has significant softness to axially asymmetric shapes, which can strongly modify the level distribution. The implications for photodeexitation of the isomer are discussed.

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