λ粒子杂质对~（18）F和~（19）F_λ结构的影响
Impurity effect of Lambda particle on the structure of 18F and 19F_Lambda
摘要：
采用密度依赖的价质子与中子之间的接触相互作用，对$sd$-壳层超核$^{19}_Λ$ F（$^{17}_Λ{\rm O}+p+n$）及其核$^{18}$ F（$^{16}{\rm O}+p+n$）进行了三体模型计算.我们发现，从第一激发态（具有$I^π=3^+$的自旋和宇称）到基态（$I^π=1^+$）的$B(E2)$值由于加入$Λ$粒子而略有降低，这表现出所谓的$Λ$粒子的收缩效应。我们还表明，在$^{19}_Λ$ F的$3^+$状态的激发能降低相比，$^{18}$ F，如在一个$p$壳核$^{6}$锂中观察到的。我们讨论了这种减少的激发能的机制，指出这是由不同的机制从$^{7}_Λ$锂。
英文摘要：
We perform three-body model calculations for a $sd$-shell hypernucleus $^{19}_Λ$F ($^{17}_Λ{\rm O}+p+n$) and its core nucleus $^{18}$F ($^{16}{\rm O}+p+n$), employing a density-dependent contact interaction between the valence proton and neutron. We find that the $B(E2)$ value from the first excited state (with spin and parity of $I^π=3^+$) to the ground state ($I^π=1^+$) is slightly decreased by the addition of a $Λ$ particle, which exhibits the so called shrinkage effect of $Λ$ particle. We also show that the excitation energy of the $3^+$ state is reduced in $^{19}_Λ$F compared to $^{18}$F, as is observed in a $p$-shell nucleus $^{6}$Li. We discuss the mechanism of this reduction of the excitation energy, pointing out that it is caused by a different mechanism from that in $^{7}_Λ$Li.
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