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arXiv 0711.2237nucl-th
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$Σ$-来自二π介子交换的核自旋轨道耦合

$Σ$-nuclear spin-orbit coupling from two-pion exchange

N. Kaiser

摘要:

利用SU(3)手征微扰理论计算了核介质中$Σ$超子的密度依赖复值自旋轨道耦合强度$U_{Σls}(k_f)+ i W_{Σls}(k_f)$。主要的长程$ΣN$相互作用来自于与中间态的$Λ$或$Σ$超子的重复一π交换。我们发现,从这个独特的长程动力学相当大的"错误的符号"的自旋轨道耦合强度$U_{Σls}(k_{f0}) \simeq -20$ MeVfm $^2$在正常的核物质密度$ρ_0 = 0.16 $ fm $^{-3}$。强$ΣN\to ΛN$转换过程同时贡献了$W_{Σls}(k_{f0}) \simeq -12$ MeVfm $^2$的虚部。当与短程贡献的估计相结合时,总的$Σ$-核自旋轨道耦合变得相当弱。

英文摘要:

Using SU(3) chiral perturbation theory we calculate the density-dependent complex-valued spin-orbit coupling strength $U_{Σls}(k_f)+ i W_{Σls}(k_f)$ of a $Σ$ hyperon in the nuclear medium. The leading long-range $ΣN$ interaction arises from iterated one-pion exchange with a $Λ$ or a $Σ$ hyperon in the intermediate state. We find from this unique long-range dynamics a sizeable ``wrong-sign'' spin-orbit coupling strength of $U_{Σls}(k_{f0}) \simeq -20$ MeVfm$^2$ at normal nuclear matter density $ρ_0 = 0.16 $fm$^{-3}$. The strong $ΣN\to ΛN$ conversion process contributes at the same time an imaginary part of $W_{Σls}(k_{f0}) \simeq -12$ MeVfm$^2$. When combined with estimates of the short-range contribution the total $Σ$-nuclear spin-orbit coupling becomes rather weak.

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