arXiv subjects

K. H. Li

Publications and source records attributed to K. H. Li.

8 recordsLinked to original sources

arXiv2026

Probing exotic multi-proton emitters: A Gamow shell model study of proton-rich fluorine and neon isotopes beyond the drip line

We investigate proton-rich systems beyond the proton drip line, focusing on the notably poorly known 13F and 15Ne and the yet unobserved 14Ne, whose structure properties remain weakly constrained. Using the Gamow shell model (GSM), which consistently incorporates both inter-nucleon correlations and couplings to the particle continuum, we study oxygen, fluorine, and neon isotopes with mass A=12-16. Taking 8C as an inert core, the GSM Hamiltonian based on an effective field theory nucleon-nucleon interaction is optimized for this proton-rich region. The constructed Hamiltonian reproduces the low-lying spectra and decay properties of fluorine and neon isotopes beyond the proton drip line. We quantify many-body configuration and average partial-wave occupancies to elucidate the structural evolution of the drip line nuclei 12-14O, 13-15F, and 14-16Ne. In particular, multi-proton separation energies and spectroscopic factors are analyzed in detail, leading to a prediction for the unresolved ground state of 13F. Furthermore, the candidate 4p emitter 14Ne is theoretically predicted for the first time, providing valuable guidance for future experimental investigations.

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arXiv2025

Gamow shell model predictions for six-proton unbound nucleus $^{20}$Si

Proton-rich nuclei beyond the proton drip line are of great interest in nuclear structure physics, due to exotic phenomena such as proton emissions and the Thomas-Ehrman shift (TES). In this work, we employ the Gamow shell model (GSM) to investigate the structure and decay of $^{20}$Si, a candidate for six-proton (6$p$) emission, which can be produced via two-neutron knockout from the drip line nucleus $^{22}$Si. We predict that its ground state decays via $6p$ emission to the ground state of $^{14}$O, with a decay energy $E_{6p} = 10.125$ MeV and a width of 371~keV. A $2^+$ state is predicted at 1.7 MeV, comparable with that in $^{18}$Mg, indicating the disappearance of the $Z=14$ magic number in $^{20}$Si. Instead, analyses of the many-body configurations and the average occupancies of the mirror states suggest the presence of $dynamic$ TES in low-lying states of $^{19}$Al/$^{19}$C and $^{20}$Si/$^{20}$C. Further evidence is provided by analyzing the contributions of different components of the GSM Hamiltonian. Moreover, this study offers the first theoretical description of $^{20}$Si and guidance for future experiments.

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arXiv2025

Gamow shell model study of the 17Ne(p, p) reaction and of isospin symmetry breaking in 18Na

The unbound nucleus 18Na, acting as an intermediate nucleus in the sequential decay of 19Mg, is situated beyond the proton drip line. We employ the coupled-channel Gamow shell model (GSM-CC) to investigate the properties of 18Na, as well as the 17Ne(p, p) cross section. GSM-CC treats the nucleus as an open quantum system and provides a unified framework for studying both nuclear structure and reaction cross sections. Our calculations reproduce the energies and partial decay widths of low-lying states in 18Na, as well as the 17Ne(p, p) cross section. Additionally, the mirror nucleus 18N is also described. The isospin symmetry breaking induced by the Coulomb interaction and continuum coupling is clearly obtained in our description of 18Na and 18N properties, arising from the extended s1/2 partial wave. The isospin symmetry breaking in the 18Na/18N pair is compared to that occurring in the mirror pair 16F/16N, whereby similarities and differences are analyzed.

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arXiv2025

Gamow shell model calculations for the Thomas-Ehrman shift in new isotopes 21Al

Proton-rich nuclei beyond the proton drip line exhibit unique phenomena, such as the Thomas-Ehrman shift (TES), providing valuable insights into nuclear stability and isospin symmetry breaking. The discovery of the lightest new isotope, 21Al, situated beyond the proton drip line, was recently reported in the experiment. In this study, we employ the Gamow shell model (GSM) to explore the TES in mirror pairs 21Al/21O, focusing on how this phenomenon affects the energy levels of these nuclei. Our calculations describe the ground state energies and reveal significant TES with large mirror energy differences in the excited mirror 1/2+ states in 21Al/21O. The large mirror energy difference is primarily due to the significant occupation of weakly bound or unbound s1/2 orbitals, resulting in the extended radial density distributions, and variations in Coulomb energy and nuclear interaction contributions between the mirror states. Additionally, the low-lying states of 21Al are also calculated with the GSM in coupled-channel (GSM-CC) representation, Furthermore, we also predict the cross-section of 20Mg(p, p) scattering, which serves as another candidate approach to study the unbound structure of 21Al in the experiment, offering a theoretical framework for studying the structure and reaction dynamics of 21Al in future experiments.

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arXiv2025

$Z=14$ Magicity Revealed by the Mass of the Proton Dripline Nucleus $^{22}$Si

Using the $Bρ$-defined isochronous mass spectrometry technique, we conducted the first mass measurement of the proton dripline nucleus $^{22}$Si. We confirm that $^{22}$Si is bound against particle emission with $S_p/S_{2p}=+1412(114)/+229(54)$ keV, fixing the proton dripline location for the Si element. By analyzing the mass differences of the neighboring $sd$-shell nuclei, we find that $^{22}$Si exhibits a doubly-magic character similar to its mirror partner $^{22}$O, and that the mirror energy difference of $^{22}$Si-$^{22}$O deviates from the predictions assuming mirror symmetry. Gamow shell-model calculations reveal that the average occupations of valence protons in $^{22}$Si are nearly identical to those of valence neutrons in $^{22}$O, supporting the $Z=14$ magicity in $^{22}$Si. The observed mirror-symmetry breaking is attributed to the extended proton distribution in $^{22}$Si arising from a small contribution of the unbound $\pi2s_{1/2}$ orbital.

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arXiv2025

Effective proton-neutron interaction in mirror nuclei

Effective proton-neutron interactions, $V_{pn}$, in mirror nuclei are systematically analyzed using the ground-state atomic masses. A mirror symmetry of $V_{pn}$ is found for bound nuclei with a standard deviation of $σ=32$ keV. However, this mirror symmetry is apparently broken for some mirror-nuclei pairs when a proton-unbound nucleus is involved in extracting the $V_{pn}$ values. Such a mirror-symmetry breaking is attributed to the Thomas-Ehrman shift of the proton-unbound nucleus and investigated by using the Gamow shell model. It is concluded that the Thomas-Ehrman shift originates mainly from reduced Coulomb energies in the proton-unbound nuclei due to the extended radial density distribution of valence protons.

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arXiv2024

Mechanisms of mirror energy difference for states exhibiting Thomas-Ehrman shift: Gamow shell model case studies of $^{18}$Ne/$^{18}$O and $^{19}$Na/$^{19}$O

The mirror energy difference (MED) of the mirror state, especially for states bearing the Thomas-Erhman shift, serves as a sensitive probe of isospin symmetry breaking. We employ the Gamow shell model, which includes the inter-nucleon correlation and continuum coupling, to investigate the MED for $sd$-shell nuclei by taking the $^{18}$Ne/$^{18}$O and $^{19}$Na/$^{19}$O as examples. Our GSM provides good descriptions for the excitation energies and MEDs for the $^{18}$Ne/$^{18}$O and $^{19}$Na/$^{19}$O. Moreover, our calculations also reveal that the large MED of the mirror states is caused by the significant occupation of the weakly bound or unbound $s_{1/2}$ waves, giving the radial density distribution of the state in the proton-rich nucleus more extended than that of mirror states in deeply-bound neutron-rich nuclei. Furthermore, our GSM calculation shows that the contribution of Coulomb is different for the low-lying states in proton-rich nuclei, which significantly contributes to MEDs of mirror states. Moreover, the contributions of the nucleon-nucleon interaction are different for the mirror state, especially for the state of proton-rich nuclei bearing the Thomas-Erhman shift, which also contributes to the significant isospin symmetry breaking with large MED.

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arXiv1998

The infrared and optical variability of OJ 287

In this paper, the long-term historical optical (UBVRI) and near-infrared (JHK) data are presented with some new observations in the optical (February 1994-January 1995) and near-infrared (November 1995) bands included for BL Lac object OJ287. The new optical data in V-band are in agreement with the results reported by other authors (Sillanpaa et al. 1996a; Arimoto et al. 1997), a close correlation between the color index of B-V and the magnitude V has been obtained from our new observations; The new infrared observations presented here indicate that the source was at a high level in the infrared band during the observation period; From the available literature, we have got that the largest variations for UBVRIJHK bands are respectively: 4.72mag, 5.93mag, 5.18mag, 4.45mag, 4.07mag, 3.87mag, 3.78mag, and 3.54mag. A strong correlation is found between the optical and near-infrared bands when the DCF method is used, which suggests that these two bands have the same emission mechanism.

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