We study the formation of single- and double-$Λ$ hypernuclei in antiproton-induced reactions relevant for the forthcoming PANDA experiment at FAIR. We use the Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) transport model with relativistic mean-fields for the description of non-equilibrium dynamics and the statistical multifragmentation model (SMM) for fragment formation. This combined approach describes the dynamical properties of strangeness and fragments in low energy $\bar{p}$-induced reactions fairly well. We then focus on the formation of double-$Λ$ hypernuclei in high energy $\bar{p}$-nucleus collisions on a primary target including the complementary $Ξ$-induced reactions to a secondary one, as proposed by the PANDA collaboration. Our results show that a copious production of double-$Λ$ hyperfragments is possible at PANDA. In particular, we provide first theoretical estimations on the double-$Λ$ production cross section, which strongly rises with decreasing energy of the secondary $Ξ$-beam.
$0s$-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…
In nuclear reactions of high energy one can simultaneously produce a lot of hypernuclei after the capture of hyperons by nuclear residues. We consider statistical disintegration of such hypernuclear systems and the connection of fragment production with the binding energies of hyperons. It is demonstrated that the hyperon binding energies can be effectively evaluated from the yields of different isotopes of hypernuclei. The double ratio method is suggested for this purpose. The advantage of this procedure is its universality and the possibility to involve many different isotopes. This method c…
We propose a novel method for producing very-neutron-rich hypernuclei and corresponding resonance states by employing charge-exchange reactions via pp($^{12}$C, $^{12}$N $K^+$)n$Λ$ with single-charge-exchange and ppp($^{9}$Be, $^{9}$C $K^+$)nn$Λ$ with double-charge-exchange, both of which produce $ΛK^+$ in a target nucleus. The feasibility of producing very-neutron-rich hypernuclei using the proposed method was analysed by applying an ultra-relativistic quantum molecular dynamics model to a $^6$Li+$^{12}$C reaction at 2 $A$ GeV. The yields of very-neutron-rich hypernuclei, signal-to-background…
Within the microscopic transport, systematic investigation of the many facets of hyperons and hypernuclei up to strangeness $S = -2$ are carried out for $^{197}$Au + $^{197}$Au and $^{40}$Ca + $^{40}$Ca at the incident energy of $3A$ GeV. The spatial, temporal and density distributions of hyperon production, absorption and freeze-out are thoroughly investigated. The rapidity and kinetic energy spectra of $Ξ$ hyperons and double $Λ$ hypernuclei are analyzed. It is revealed that the chemical balance of hyperon production is established in baryon-baryon channels while the opposite is found in bar…
We investigate $S=-1$ and $-2$ hypernuclei with $A=4-8$ employing the Jacobi-NCSM approach and in combination with baryon-baryon interactions derived within the frame work of chiral effective field theory. The employed interactions are transformed using the similarity renormalization group (SRG) so that the low- and high-momentum states are decoupled, and, thereby,convergence of the binding energies with respect to model space can be significantly speeded up. Such an evolution is however only approximately unitary when the so-called SRG induced higher-body forces are omitted. We first explore …
A comparison of light hypernuclei production, from UrQMD+coalescence and the thermal model, in heavy ion collisions over a wide range of beam energies and system sizes is presented. We find that both approaches provide generally similar results, with differences in specific details. Especially the ratios of hypertriton to $Λ$ are affected by both the source radius $Δr$ of the coalescence procedure as well as canonical effects. On the other hand, the double ratio $S_3$ is almost independent of canonical effects, which is in contrast to coalescence. Thus, both the beam energy dependence and cent…
Recent experiments have presented more accurate data on the $ΛΛ$-binding energies of a few $ΛΛ$- hypernuclei. This is important as the $ΛΛ$- bond energies ($ΔB_{ΛΛ}$) of double-$Λ$ hypernuclei provide a measure of the in-medium strength of the $ΛΛ$ interaction. A mass formula, optimized with the newly available $ΛΛ$ binding energy data, is used to estimate the binding energy and bond energy over a wide range of hypernuclei. The $ΔB_{ΛΛ}$ values calculated with this mass formula are in good agreement with the experimental data, predictions of the quark mean-field (QMF) model and the relativisti…
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…
The J=1/2 iso-doublet double-$Λ$-hypernuclei, namely, ${}_{ΛΛ}^{5}$H and ${}_{ΛΛ}^{5}$He, are examined as the three-body cluster states, $ΛΛt$ ($t\equiv {}^3$H or triton) and $ΛΛh$ ($h\equiv {}^3$He or helion), respectively, in a model independent framework utilizing pionless halo effective theory. Both singlet and triplet states of the constituent $ΛT$ ($T\equiv t,h$) sub-system are used in the elastic channel for the study of $_Λ^4$H$-Λ$ and $_Λ^4$He$-Λ$ scattering processes. A prototypical leading order investigation using a sharp momentum cut-off regulator, irrespective of the type of the …
Single and double coincidence nucleon spectra in the weak decay of Lambda hypernuclei
最近在超核弱衰变领域取得了一些进展，特别是关于中子与质子引起的λ非介子衰变率之比G_n/G_p的研究。由此得到的G_n/G_p值与纯理论估计值一致，从而为解决一个长期存在的难题提供了证据。在这里，我们提出了一种替代方法的问题，通过局部密度近似的基础上扩展到有限核的核物质形式主义。本文的工作是由无模型依赖数据确定G_n/G_p的迫切性所激发的。单介子交换势用于描述单核子和双核子诱导的衰变，Lambda N -> n N和Lambda N N -> n N N。对于后者，在微观方法内处理，通道λ n n -> n n n和λ p p -> n p p除了已经考虑的模式λ n p -> n n p之外，还包括在先前的研究中以现象学的方式。用核内级联程序模拟了末态核子在剩余核中的传播。我们评估了C-12-Lambda非介子衰变的单和双符合核子谱。通过我们的预测与KEK符合数据的比较，我们确定了该超核的G_n/G_p=0.43 \pm 0.10，证实了以前的有限核分析。
The BNL-AGS E906 experiment was the first fully electronic experiment to produce and study double hypernuclei with large statistics. Two dominant structures were observed in the correlated $π^-$--$π^-$ momentum matrix at (p$_{π-H}$,p$_{π-L}$) = (133,114) MeV/c and at (114,104) MeV/c. In this work we argue that the interpretation of the structure at (133,114) MeV/c in terms of $^3_Λ$H+$^4_Λ$H pairs is questionable. We show, that neither a scenario where the hypernuclei are produced after capture of a stopped $Ξ^-$ by a $^9$Be nucleus nor interactions of energetic $Ξ^-$ with $^9$Be nuclei in the…
Bound state properties of few single and double-$Λ$ hypernuclei is critically examined in the framework of core-$Λ$ and core+$Λ+Λ$ few-body model applying hyperspherical harmonics expansion method (HHEM). The $ΛΛ$ potential is chosen phenomenologically while the core-$Λ$ potential is obtained by folding a phenomenological $ΛN$ interaction into the density distribution of the core. The depth of the effective $ΛN$ potential is adjusted to reproduce the experimental data for the core-$Λ$ subsystem. The three-body Schrödinger equation is solved by hyperspherical adiabatic approximation (HAA) to ge…
Production of doubly strange hypernuclei via Ξ- doorways in the 16O(K-, K+) reaction at 1.8 GeV/c
本文在扭曲波脉冲近似下研究了双电荷交换~（16）O（K-，K+）反应中双奇异超核16 ~-C和16 ~ Λ ~ ΛC的产生.在入射动量pK- = 1.8 GeV/c，散射角θlab = 0^{ \circ }的一步机制下，估算了K+的包容谱，即K-p \to K+ p- via p-door由p-p-ΛΛ耦合引起.计算结果表明，在16 ~ C中，14 C（0+，2+）\otimes s ~（？）~ p ~~（？）~ p ~（？）~（？）~ p ~（？）~（？）~ p ~（？）~（？）~ p ~（？）~ p ~（？）~ p ~（？）~ p ~（？）~（？）~ p ~（？）~（？）~（（1/2-，3/2-）\otimes在16 ℃时由于高动量转移q = \approx 400 MeV/c而发生电子跃迁.这些态的混合几率约为5- 9%。然而，具有14 C（0+）\otimes s2Λ的0+基态和具有14 C（2+）\otimes s2 Λ的2+激发态的布居非常小。能谱对核中N-ΛΛ耦合强度的敏感性使我们能够提取核中N-ΛΛ动力学的本质，核（K-，K+）反应可以扩展我们对S = -2世界的认识。
We investigate double $Λ$ hyperfragment formation from the statistical decay of double $Λ$ compound nuclei produced in the $Ξ^-$ absorption at rest in light nuclei, $^{12}\mathrm{C}$, $^{14}\mathrm{N}$ and $^{16}\mathrm{O}$. We examine the target and the $ΛΛ$ bond energy dependence of the double $Λ$ hyperfragment formation probabilities, especially of those double hypernuclei observed in experiments. For the $^{12}\mathrm{C}$ ($^{14}\mathrm{N}$) target, the formation probabilities of $^{6}_{ΛΛ}\mathrm{He}$ and $^{10}_{ΛΛ}\mathrm{Be}$ ($^{13}_{ΛΛ}\mathrm{B}$) are found to be reasonably large as…
The production of strange particles (kaons, hyperons) and hypernuclei in light charged particle induced reactions in the energy range of a few GeV (2-15 GeV) has become a topic of active research in several facilities (e.g., HypHI and PANDA at GSI and/or FAIR (Germany), JLab (USA), and JPARC (Japan)). This energy range represents the low-energy limit of the string models (degree of freedom: quark and gluon) or the high-energy limit of the so-called spallation models (degree of freedom: hadrons). A well known spallation model is INCL, the Liège intranuclear cascade model (combined with a de-exc…
Low-energy pion-pion scattering in the $pp \to ppπ^{+}π^{-}$ and $p\bar p \to p\bar pπ^{+}π^{-}$ reactions
我们评估的贡献，π介子再散射的$p p \to p p π^+ π^-$和$p \bar p \to p \bar p π^+ π^-$反应。我们将我们的结果与接近阈值的实验数据进行比较。发现π介子-π介子再散射的贡献可以忽略不计。对未来在达姆施塔特GSI高能储存环（HESR）上使用PANDA探测器的实验进行了预测。讨论了如何切断主导的Roper共振和双$Δ$激发机制，导致最终态的$p p π^+ π^-$通道。给出了动量转移、横向动量、有效双π介子质量、π介子间相对方位角和π介子快度的微分分布。
