Shell-model calculations that include both Lambda and Sigma configurations with p-shell cores are used to interpret gamma-ray transitions in Lambda-7Li, -9Be, -10B, -11B, -12C, -15N, and -16O observed with the Hyperball array of Ge detectors. It is shown that the data puts strong constraints on the spin dependence of the Lambda-N effective interaction and that the Lambda-Sigma coupling plays an important role.
Charge symmetry breaking (CSB) is particularly strong in the A=4 mirror hypernuclei $_Λ^4$H--$_Λ^4$He. Recent four-body no-core shell model calculations that confront this CSB by introducing $Λ$-$Σ^0$ mixing to leading-order chiral effective field theory hyperon-nucleon potentials are reviewed, and a shell-model approach to CSB in p-shell $Λ$ hypernuclei is outlined.
Halo Structures in p-Shell Hypernuclei with Natural Orbitals
Technische Universität Darmstadt（达姆施塔特工业大学）；Institut für Kernphysik, Fachbereich Physik, Technische Universität Darmstadt（达姆施塔特工业大学物理系核物理研究所）；Helmholtz Forschungsakademie Hessen für FAIR, GSI Helmholtzzentrum（黑森FAIR亥姆霍兹研究中心GSI亥姆霍兹中心）
Energy spectra of $0s$-orbit $Λ$ states in $p$-shell $Λ$ hypernuclei ($^{A}_ΛZ$) and those in $^{19}_Λ\textrm{F}$ are studied with the microscopic cluster model and antisymmetrized molecular dynamics using the $G$-matrix effective $ΛN$ ($ΛNG$) interactions. Spin-dependent terms of the ESC08a version of the $ΛNG$ interactions are tested and phenomenologically tuned to reproduce observed energy spectra in $p$-shell $^{A}_ΛZ$. Spin-dependent contributions of the $ΛN$ interactions to spin-doublet splitting and excitation energies are discussed. Energy spectra for unobserved excited states in $p$-s…
We explore the systematics of ground-state and excitation energies in singly-strange hypernuclei throughout the helium and lithium isotopic chains --- from $^5_Λ$He to $^{11}_Λ$He and from $^7_Λ$Li to $^{12}_Λ$Li --- in the ab initio no-core shell model with importance truncation. All calculations are based on two- and three-baryon interaction from chiral effective field theory and we employ a similarity renormalization group transformation consistently up to the three-baryon level to improve the model-space convergence. While the absolute energies of hypernuclear states show a systematic vari…
We extend the recently developed Jacobi no-core shell model to hypernuclei. Based on the coefficients of fractional parentage for ordinary nuclei, we define a basis where the hyperon is the spectator particle. We then formulate transition coefficients to states that single out a hyperon-nucleon pair which allow us to implement a hypernuclear many-baryon Hamiltonian for $p$-shell hypernuclei. As a first application, we use the basis states and the transition coefficients to calculate the ground states of $^{4}_Λ$He, $^{4}_Λ$H, $^{5}_Λ$He, $^{6}_Λ$He, $^{6}_Λ$Li, and $^{7}_Λ$Li and, additionally…
$0s$-orbit $Λ$ states in $p$-shell double-$Λ$ hypernuclei ($^{\ \,A}_{ΛΛ}Z$), $^{\ \,8}_{ΛΛ}\textrm{Li}$, $^{\ \,9}_{ΛΛ}\textrm{Li}$, $^{10,11,12}_{\ \ \ \ \ ΛΛ}\textrm{Be}$, $^{12,13}_{\ \ ΛΛ}\textrm{B}$, and $^{\,14}_{ΛΛ}\textrm{C}$ are investigated. Microscopic cluster models are applied to core nuclear part and a potential model is adopted for $Λ$ particles. The $Λ$-core potential is a folding potential obtained with effective $G$-matrix $Λ$-$N$ interactions, which reasonably reproduce energy spectra of $^{A-1}_{\,Λ}Z$. System dependence of the $Λ$-$Λ$ binding energies is understood by the…
Grand Accélérateur National d’Ions Lourds (GANIL), CEA/DSM - CNRS/IN2P3（大重离子加速器（GANIL））；Department of Physics, Tohoku University（东北大学物理系）；Nishina Center, RIKEN（理化学研究所西村中心）；Université Paris-Saclay, CNRS/IN2P3, IJClab（巴黎萨克雷大学）；School of Nuclear Science and Technology, University of Chinese Academy of Sciences（中国科学院大学核科学与技术学院）
We generalize the Jacobi no-core shell model (J-NCSM) to study double-strangeness hypernuclei. All particle conversions in the strangeness $S=-1,-2$ sectors are explicitly taken into account. In two-body space, such transitions may lead to the coupling between states of identical particles and of non-identical ones. Therefore, a careful consideration is required when determining the combinatorial factors that connect the many-body potential matrix elements and the free-space two-body potentials. Using second quantization, we systematically derive the combinatorial factors in question for $S=0,…
Implications of Recent Data on Non-mesonic Decay of Light Lambda-hypernuclei
我们用布洛克和达利茨的唯象模型分析了轻λ-超核（直到^12_λ C）的非介子衰变的最新数据。将自旋-同位旋相关的Lambda N -> NN反应速率拟合到六个数据点，我们预测了合理一致的剩余数据。我们发现，尽管Lambda N -> NN相互作用的短程性质，p壳层超核的非介子衰变似乎是由p壳层中子强烈诱导的。此外，最近的数据表明，在强子水平上得到很好证明的Delta I = 1/2规则在核介质中可能不是神圣的，Delta I = 3/2相互作用似乎需要描述λ超核的非介子衰变。
$ΛN$ spin-spin and spin-orbit splittings in low-lying excitation spectra are investigated for $p$-shell $Λ$ hypernuclei on the basis of the microscopic structure calculation within the antisymmetrized molecular dynamics, where the $ΛN$ $G$-matrix interaction derived from the baryon-baryon interaction model ESC (extended soft core) is used. It is found that the ground-state spin-parity is systematically reproduced in the $p$-shell $Λ$ hypernuclei by tuning the $ΛN$ spin-spin and spin-orbit interactions so as to reproduce the experimental data of $^{4}_Λ$H, $^{7}_Λ$Li and $^9_Λ$Be. Furthermore, …
We have systematically investigated the excitation spectra of $p$-shell hypernuclei within the shell model based on the nucleon-nucleon and hyperon-nucleon interactions. For the effective nucleon-nucleon interaction, we adopt the Gogny force instead of the widely-used empirical $p$-shell Cohen-Kurath interaction, while the hyperon-nucleon interaction takes the $ΛN$ interaction including the $ΛN$-$ΣN$ coupling effect. We find that the shell model with the Gogny force can give reasonable descriptions of both spectra and binding energies of the $p$-shell nuclei. With this confidence, combined wit…
我们讨论了超核中不同重子态的混合和各种奇异核的形成。首先，生产的中子丰富的λ超核的（π-，K+）反应被认为是，和一步生产通过重子混合物在最终状态以及在初始状态进行了讨论。然后，以$^{12}_{ΛΛ}$ Be为例，研究了p壳层λ超核中的λ- Xi N混合.最后一个主题是专门生产的θ五夸克核（pentanuclei）。我们提出了一种无反冲Theta产生的反应。
We employ a feed-forward artificial neural network to extrapolate at large model spaces the results of {\it ab-initio} hypernuclear No-Core Shell Model calculations for the $Λ$ separation energy $B_Λ$ of the lightest hypernuclei, $^3_Λ$H, $^4_Λ$H and $^4_Λ$He, obtained in computationally accessible harmonic oscillator basis spaces using chiral nucleon-nucleon, nucleon-nucleon-nucleon and hyperon-nucleon interactions. The overfitting problem is avoided by enlarging the size of the input dataset and by introducing a Gaussian noise during the training process of the neural network. We find that a…
The separation energies of the isospin triplet $^7_Λ\mathrm{He}$, $^7_Λ\mathrm{Li^{*}}$, $^7_Λ$Be, and the $T=1/2$ doublet $^8_Λ$Li, $^8_Λ$Be are investigated within the no-core shell model. Calculations are performed based on a hyperon-nucleon potential derived from chiral effective field theory at next-to-leading order. The potential includes the leading charge-symmetry breaking (CSB) interaction in the $Λ$N channel, whose strength has been fixed to the experimentally known difference of the $Λ$ separation energies of the mirror hypernuclei $^4_Λ\mathrm{He}$ and $^4_Λ\mathrm{H}$. It turns ou…
The structure of single-$Λ$ hypernuclei is studied using the chiral hyperon-nucleon potentials derived at leading order (LO) and next-to-leading order (NLO) by the Jülich--Bonn--Munich group. Results for the separation energies of $Λ$ single-particle states for various hypernuclei from $^5_Λ$He to $^{209}_{\,\,\,\,\,Λ}$Pb are presented for the LO interaction and the 2013 (NLO13) and 2019 (NLO19) versions of the NLO potentials. It is found that the results based on the LO potential show a clear tendency for overbinding while those for the NLO13 interaction underbind most of the considered hyper…
