Abstract

The method of superoperators in Liouville space was applied to study spectral properties of hot nuclei. It is shown that properly defined fermionic superoperators allow us to generalize the equation-of-motion method to hot nuclei. Within the superoperator approach, for the nuclear model with separable particle–hole residual interaction of Landau–Migdal type, we derived the equations of thermal quasiparticle random phase approximation, which allow the spectral densities and strength functions of charge-exchange and charge-neutral excitations of hot nuclei to be calculated in a thermodynamically consistent way, i.e., without violating the principle of detailed balance. For the quasiparticle-phonon nuclear model, a thermodynamically consistent way is proposed for going beyond the random phase approximation by considering the interaction of thermal phonons. Using the Donnelly–Walecka method and the superoperator approach, expressions for cross sections of semileptonic weak reactions with hot nuclei are obtained.

中文翻译：

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热核理论和天体物理应用的超级算子方法：I—热核的光谱特性

摘要

应用刘维尔空间超算符方法研究热核的光谱性质。结果表明，正确定义的费米子超级算子使我们能够将运动方程方法推广到热核。在超级算子方法中，对于具有 Landau-Migdal 类型的可分离粒子-空穴残余相互作用的核模型，我们推导出了热准粒子随机相位近似方程，它允许电荷交换和电荷中性激发的光谱密度和强度函数以热力学一致的方式计算热核的数量，即不违反详细平衡原理。对于准粒子-声子核模型，通过考虑热声子的相互作用，提出了一种热力学一致的方法来超越随机相位近似。利用Donnelly-Walecka方法和超算子方法，得到了热核半轻弱反应截面的表达式。