论文标题
$^{19} $ b的三体结构
Three-body structure of $^{19}$B: Finite-range effects in two-neutron halo nuclei
论文作者
论文摘要
$^{19} $ b的结构和$ b（e1）$过渡强度在$^{17} \ text {b}+n+n $模型中进行了研究，这是由于最近的实验触发的，该实验表明$^{19} $ b展示了一个明显的两中性晕圈结构。对实验数据的初步分析是通过采用触点$ n $ - $ n $互动来进行的，这些互动众所周知，这些互动会低估其他光晕核中的$ s $波含量，例如$^{11} $ li。在目前的工作中，使用有限的两体相互作用的三体超球形形式主义用于描述$^{19} $ b。特别是，将使用两个不同的有限范围$ n $ - $ n $交互作用，以及一个简单的中央高斯潜力，其范围逐渐减小。目的是确定细胞核的主要特性，并调查使用类似接触的$ n $ - $ n $电位时它们的变化。还要特别注意用于说明三体效果的处方的依赖，即三体力量或密度依赖于$ n $ -n $ n $的潜力。我们发现，三体模型加有限范围的电位提供了$^{19} $ b的描述，与实验数据一致。结果本质上独立于两体电位的短途细节，从而产生$（s_ {1/2}）^2 $含量约为55％，显然大于初始估计。对三体效应的处方也很少发现依赖性。总计计算的$ b（E1）$强度与实验结果兼容，尽管我们略微高估了$ db（E1）/d \ varepsilon $分布的低能峰附近的数据。最后，我们表明，减少$ n $ - $ n $相互作用范围会大大减少$ s $ - 波贡献，然后在使用触点交互的计算中预期应预期。
The structure and $B(E1)$ transition strength of $^{19}$B are investigated in a $^{17}\text{B}+n+n$ model, triggered by a recent experiment showing that $^{19}$B exhibits a well pronounced two-neutron halo structure. Preliminary analysis of the experimental data was performed by employing contact $n$-$n$ interactions, which are known to underestimate the $s$-wave content in other halo nuclei such as $^{11}$Li. In the present work, the three-body hyperspherical formalism with finite-range two-body interactions is used to describe $^{19}$B. In particular, two different finite-range $n$-$n$ interactions will be used, as well as a simple central Gaussian potential whose range is progressively reduced. The purpose is to determine the main properties of the nucleus and investigate how they change when using contact-like $n$-$n$ potentials. Special attention is also paid to the dependence on the prescription used to account for three-body effects, i.e., a three-body force or a density-dependent $n$-$n$ potential. We have found that the three-body model plus finite-range potentials provide a description of $^{19}$B consistent with the experimental data. The results are essentially independent of the short-distance details of the two-body potentials, giving rise to an $(s_{1/2})^2$ content of about 55%, clearly larger than the initial estimates. Very little dependence has been found as well on the prescription used for the three-body effects. The total computed $B(E1)$ strength is compatible with the experimental result, although we slightly overestimate the data around the low-energy peak of the $dB(E1)/d\varepsilon$ distribution. Finally, we show that a reduction of the $n$-$n$ interaction range produces a significant reduction of the $s$-wave contribution, which then should be expected in calculations using contact interactions.
