arXiv subjects

Shi Yuan Ding

Publications and source records attributed to Shi Yuan Ding.

6 recordsLinked to original sources

arXiv2026

Single- and Double-$Λ$ Hypernuclear Correlations Calibrate $ΛΛ$ Interaction Energies

Double-$Λ$ hypernuclei are essential for probing the $ΛΛ$ interaction in the double-strangeness $S=-2$ sector, yet the scarcity of experimental data severely limits systematic predictions. We present an evaluation framework based on nuclear many-body theory that exploits the intrinsic structural similarity between single-$Λ$ and double-$Λ$ systems to transfer empirical constraints from the well-mapped $S = -1$ sector to the $S = -2$ sector. By analyzing theoretical deviations of binding energies in light single- and double-$Λ$ hypernuclei, we identify a robust linear correlation between two sectors. This correlation enables a statistical evaluation of double-$Λ$ separation energies ($B_{ΛΛ}$) and $ΛΛ$ interaction energies ($ΔB_{ΛΛ}$) for heavier double-$Λ$ hypernuclei, by drawing on a wealth of empirical data from the single-$Λ$ sector with quantified uncertainties. Our results show that evaluated $ΔB_{ΛΛ}$ values, while consistent with existing data, are systematically larger than direct relativistic density functional predictions constrained only by the NAGARA event. This discrepancy suggests that standard mean-field-based extrapolations may underestimate $ΛΛ$ correlations and other many-body effects, motivating an evaluation-based correction that offers crucial benchmarks for future $S = -2$ experiments at facilities such as HIAF and J-PARC.

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arXiv2025

Impact of $Ξ$-Hypernuclear Constraints on Relativistic Equation of State and Properties of Hyperon Stars

Significant uncertainties persist in describing the equation of state and internal structure of hyperon stars due to the limited understanding of the mechanisms underlying hyperon interactions. Constraining the interaction parameter space through a combination of the latest astronomical observations and hypernuclear physics experiments is therefore essential. In this study, we incorporate experimental constraints from $Ξ$ hypernuclear physics on top of $Λ$ hyperons considered in \citet{Sun2023APJ942.55}. Specifically, based on updated measurements of hyperon separation energies from $Ξ$ hypernuclear experiments, sets of $ΞN$ effective interactions are constructed and a linear correlation between their scalar ($σ$) and vector ($ω$) coupling strength ratios is proposed as a constraint derived from $Ξ$ hypernuclear physics. Together with experimental correlations and astronomical observational data, four types of analyses are performed to constrain hyperon-nucleon interactions and the properties of hyperon stars. Compared to the vector $ω$ meson-hyperon coupling, the introduction of linear correlations in hypernuclear physics imposes a more substantial constraint on the scalar $σ$ meson-hyperon coupling, significantly enhancing its coupling strength and thereby ensuring the stiffness of the equation of state, highlighting the crucial role of hypernuclear studies in solving the hyperon puzzle problem. Consequently, a maximum mass of around $2M_{\odot}$ can be achieved with all five interactions considered in this study under the combined constraints from astronomical observations and nuclear physics. With more reliably estimated hyperon-nucleon contributions, the uncertainties in both the fractions and the threshold densities at which hyperons appear inside neutron stars are notably reduced, along with those in the mass-radius predictions.

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arXiv2024

Density-dependent relativistic mean-field model for $ Ξ^{-} $ hypernuclei

In hypernuclear systems, interactions involving nucleons and hyperons are intricately influenced by the surrounding particles, particularly by the density and the isospin feature of the nuclear medium. In this work, the relativistic mean-field (RMF) theory is adopted to describe the structure of several typical $Ξ^{-}$ hypernuclei. New sets of $ΞN$ effective interactions, by taking a density-dependent meson-nucleon/hyperon coupling perspective, are developed by fitting experimental data on the $Ξ^{-}$ hyperon $1s$ and $1p$ state separation energy of $^{15}_{Ξ^{-}}$C as well as the $1p$ state separation energy of $^{13}_{Ξ^{-}}$B. The density-dependent behavior of meson-hyperon coupling strengths sensitively affects the description of hyperon single-particle levels. In fact, the density-dependent meson-baryon coupling strengths introduce additional rearrangement contributions to the hyperon self-energy. Correspondingly, detailed forms of density dependence in these coupling strengths and different considerations of meson-baryon coupling channels will impact the hyperon single-particle properties within hypernuclei. Especially with the additional inclusion of the isovector scalar $ δ$ meson, the significant enhancement of rearrangement terms in the effective interaction DD-ME$δ$ impacts the shape of the hyperon potential and alters the characteristics of the isovector channel dynamics balance in the effective nuclear force. Relevant research underscores the importance of precisely accounting for in-medium effects in hyperon-nucleon interactions and incorporating a more comprehensive set of meson-exchange degrees of freedom in effective nuclear forces, offering a potential solution for more self-consistently describing the featured hyperon single-particle behavior of various hypernuclei and for reducing uncertainties in theoretical descriptions.

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arXiv2024

Charmed hypernuclei within density-dependent relativistic mean-field theory

The charmed $ Λ_{c}^{+} $ hypernuclei are investigated within the framework of the density-dependent relativistic mean-field (DDRMF) theory. Starting from the empirical hyperon potential in symmetric nuclear matter, obtained through microscopic first-principle calculations, two sets of $Λ_c N$ effective interactions were derived by fitting the potentials with minimal uncertainty (Fermi momentum $k_{F,n} = 1.05~\rm{fm}^{-1}$) and near saturation density ($k_{F,n} = 1.35~\rm{fm}^{-1}$). These DDRMF models were then used to explore the $Λ_{c} N$ effective interaction uncertainties on the description of hypernuclear bulk and single-particle properties. A systematic investigation was conducted on the existence of bound $Λ_{c}^{+}$ hypernuclei. The dominant factors affecting the existence and stability of hypernuclei were analyzed from the perspective of the $Λ_{c}^{+}$ potential. It is found that the hyperon potential is not only influenced by the Coulomb repulsion, but by an extra contribution from the rearrangement terms due to the density dependence of the meson-baryon coupling strengths. Therefore, the rearrangement term significantly impacts the stability description for light hypernuclei, while for heavier hypernuclei, the contribution from Coulomb repulsion becomes increasingly significant and eventually dominant. The discussion then delves into the bulk and single-particle properties of charmed hypernuclei using these models. It is found that even when different models yield similar hyperon potentials for nuclear matter, different treatments of nuclear medium effects could lead to disparities in the theoretical description of hypernuclear structures. This study indicates that constraints on the $ Λ_{c} N $ interaction at finite densities are crucial for the study of $ Λ_{c}^{+} $ hypernuclear structures.

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arXiv2023

Density-dependent relativistic mean field approach and its application to single-$Λ$ hypernuclei in Oxygen isotopes

The in-medium feature of nuclear force which includes both nucleon-nucleon ($NN$) and hyperon-nucleon ($ΛN$) interactions impacts the description of single-$Λ$ hypernuclei. With the alternated mass number or isospin of hypernuclei, such effects could be unveiled by analyzing systematical evolution of the bulk and single-particle properties. From a density-dependent meson-nucleon/hyperon coupling perspective, a new $ΛN$ effective interaction in the covariant density functional (CDF) theory, namely DD-LZ1-$\Lambda1$, is obtained by fitting the experimental data of $Λ$ separation energies for several single-$Λ$ hypernuclei. It is then adopted to study the structure and transition properties of single-$Λ$ hypernuclei in Oxygen isotopes, comparing with several selected CDF Lagrangians. Discrepancy is observed explicitly in the isospin evolution of $\Lambda1p$ spin-orbit splitting with various effective interactions, ascribed to their divergence of the meson-hyperon coupling strengths with increasing density. In particular, the density-dependent CDFs introduce an extra contribution to enhance the isospin dependence of the splitting, which is originated from the rearrangement terms of $Λ$ self-energies. In addition, the characteristics of hypernuclear radii are studied along the isotopic chain. Owing to the impurity effect of $Λ$ hyperon, a size shrinkage is observed in the matter radii of hypernuclei as compared to their cores of normal nuclei, while its magnitude is elucidated further to correlate with the incompressibility of nuclear matter. Besides, there exists a sizable model-dependent trend that $Λ$ hyperon radii evolve with the neutron number, which is decided partly by the in-medium $NN$ interactions as well as the core polarization effects.

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arXiv2022

Quenched Λ spin-orbit splitting by relativistic Fock diagram in single-Λ hypernuclei

We extend the relativistic Hartree-Fock (RHF) theory to study the structure of single-$Λ$ hypernuclei. The density dependence is taken in both meson-nucleon and meson-hyperon coupling strengths, and the induced $Λ$-nucleon ($ΛN$) effective interactions are determined by fitting $Λ$ separation energies to the experimental data for several single-$Λ$ hypernuclei. The equilibrium of nuclear dynamics described by the RHF model in normal atomic nuclei, namely, the balance between nuclear attractive and repulsive interactions, is then found to be drastically changed in single-$Λ$ hypernuclei, revealing a different role of Fock terms via $Λ$ hyperon from the nucleon exchange. Since only one hyperon exists in a single-$Λ$ hypernucleus, the overwhelmed $ΛN$ and $ΛΛ$ attractions via the Hartree than the $ΛΛ$ repulsion from the Fock terms require an alternation of meson-hyperon coupling strengths in RHF to rebalance the effective nuclear force with the strangeness degree of freedom, leading to an improved description of $Λ$ Dirac mass and correspondingly a systematically reduced $σ$-$Λ$ coupling strength $g_{σΛ}$ in current models as compared to those relativistic mean-field (RMF) approaches without Fock terms. As a result, the effective $Λ$ spin-orbit coupling potential in the ground state of hypernuclei is suppressed, and these RHF models predict correspondingly a quenching effect in $Λ$ spin-orbit splitting in comparison with the RMF cases. Furthermore, the $Λ$ spin-orbit splitting could decrease efficiently by evolving the hyperon-relevant couplings $g_{σΛ}$ and $g_{ωΛ}$ simultaneously, where to reconcile with the empirical value the RHF models address a larger parameter space of meson-hyperon couplings.

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