THEORETICAL STUDY OF NUCLEI WITH STRANGENESS

该项目由五大课题组成，主要成果如下：(1)对光超核的光谱学进行了微观三体和四体簇模型计算，证实了Λ参与作用下的核芯收缩。分析了自旋-自旋和自旋轨道ΛN相互作用的作用。结果表明，Σ组分掺入质量-4 Λ超核低洼态具有反映所采用的YN相互作用性质的特色化作用。通过DWIA计算，成功地解释了飞行中和停止时的（K-, π）反应谱。(2)已经提出了几种理论尝试来评估双-Λ超核的产生速率。在典型的S = -2体系中也研究了超子混合的影响。(3)值得注意的是，已经提出了几种新的YN和YY相互作用的介子理论模型，并在超核结构中进行了测试。此外，夸克模型还提出了重子-重子相互作用的几个版本。将夸克模型推广到核物质中氢粒子的相互作用。(4)为了解释新的超核弱衰变（寿命）实验数据，除了OPE过程外，还对相关双介子交换过程和直接夸克过程进行了评价。人们发现，两者都有一定的有利影响，但并不总是充分的。(5)在研究项目中应用和发展了重要的计算方法：典型的例子是量子分子动力学（QMD）方法、高斯基耦合重排通道方法和复标度法。

The project consists of five major subjects which lead to the following achievements. (1) The microscopic three- and four-body cluster model calculations have been carried out for spectroscopy of light hypernuclei : The shrinkage of the nuclear core under the effect of Λ participation has been confirmed. The role of spin-spin and spin-orbit ΛN interactions has been analysed. It has been revealed that the admixture of Σ component into the mass-4 Λ hypernuclear low-lying states has a characteristic role reflecting the properties of YN interaction adopted. The in-flight and stopped (K-, π) reaction spectra are successfully explained by the DWIA calculation. (2) Several theoretical attempts have been presented to evaluate the production rates of double-Λ hypernuclei. The effect of hyperon mixing has been also investigated in typical S = -2 systems. (3) It is remarkable that several meson theoretical models of new YN and YY interactions have been presented to be tested in the hypernuclear structure. Moreover the quark models also presented several versions of the baryon-baryon interactions. The quark model has been extended to evaluate the interaction of the H particles in nuclear matter. (4) In order to explain new experimental data of hypernuclear weak decays (lifetimes), the correlated two-pion exchange process and the direct (quark process were evaluated in addition to the OPE process. It has been found that they have both certain favorable effects but are not always sufficient. (5) The important calculational methods have been applied and developed in the research project : the typical examples are the quantum molecular dynamics (QMD) approach, the Gaussian basis coupled-rearrangement channel method and the complex scaling method.