Molecular Structures of Strangeness Light-nuclei and their Response Spectra

1.在有限射程N-N和Λ-N有效相互作用的基础上，对奇异核进行了平均场计算：Hartree-Fock（HF）和密度相关的Hartree-Fock（DDHF）计算。我们讨论了^<17>_ΛO和^5_ΛHe的结构以及由于加入Λ超子而引起的核极化效应。我们强调指出，在DDHF中，（Os）_Λ的核极化（重排）能ΔE_N为1.2MeV，（Op）_Λ的核极化（重排）能ΔE_N为1.1MeV.核的总能量E_N降低的原因是由于加入Λ使核子的sp.能量e_α变深。ΔE_N的能量取决于N-N有效相互作用的性质和N-N有效相互作用再现实验数据的能力。2.奇异核的产生及其响应谱我们提出了一个DWIA核反应的“最佳费米平均近似”。我们用它计算了^<12>C（π^+，K^+）反应的A准自由能谱，并与实验数据进行了比较。计算结果表明，由于能量依赖性源于最佳费米平均t矩阵的性质，计算的能谱与实验数据非常吻合。然后我们将它的（π^-，K^+）谱推广到^<12>C和^<28>Si靶上，以便从数据中提取π ^-核势的性质。我们发现，^ Si的π ^-核势<28>的斥力为V^0_[相似或相等] +20 +40 MeV，而伍兹-撒克逊型势的吸收相当大，为-10-30 MeV，而再现π ^-原子X射线数据的π ^-核势将再现（π^-，K^+）光谱。此外，我们预测，^4_ΛHe基态约有20%通过（停止K^-，π^-）反应中的π组分填充，使用耦合的（3 N-Λ）+（3 N-π）模型。

1.Mean-field calculations for strangeness-nucleiHartree-Fock (HF) and Density-dependent Hartree-Fock (DDHF) calculations for hypernuclei are performed on the basis of ΝΝ and ΛΝ effective interactions with a finite-range. We discuss structures of ^<17>_ΛO and ^5_ΛHe and core-polarization effects arising from the addition of the Λ-hyperon. We stress that the core-polarization (rearrangement) energy ΔE_N is 〜2 MeV for (Os)_Λ and 〜1 MeV for (Op)_Λ in the DDHF. The reason why the total energy E_N of the core is reduced is because the nucleon s.p. energy e_α becomes deeper by the addition of the Λ. Energies of ΔE_N depend on the nature of the ΝΝ effective interaction and the capacity of the ΛΝ effective interaction to reproduce the experimental data.2.Production of strangeness-nuclei and their response spectraWe propose an "optimal Fermi-averaging approximation" to nuclear reactions within the DWIA. We apply it to calculate A quasi-free spectra from ^<12>C(π^+,K^+) reactions, and compare them with experimental data. The results show that the calculated spectra are in excellent agreements with the data, because the energy-dependence originates from the nature of the optimal Fermi-averaging t-matrix. Then we extend it (π^-,K^+) spectra on ^<12>C and ^<28>Si targets in order to extract properties of Σ^--nucleus potential from the data. We find that the Σ^--nucleus potential for ^<28>Si has a repulsion of V^0_Σ【similar or equal】 +20 〜 +40 MeV, and a sizable absorption of -10 〜 -30 MeV for a Woods-Saxon type potential, and that a Σ^--nucleus potential reproducing the Σ^-atomic x-ray data, would reproduce the (π^-,K^+) spectra. Moreover, we predict that the ^4_ΛHe ground state is populated by about 20% via Σ components in (stopped K^-,π^-) reactions, using a coupled (3Ν-Λ)+(3Ν-Σ) models.