论文标题
阐明有限温度准粒子随机相近似
Elucidating the finite temperature quasiparticle random phase approximation
论文作者
论文摘要
在众多天体物理场景中，例如核心 - 崩溃的超新星和中子星合并，如在重离子碰撞实验中，已显示热核激发态之间的过渡起着重要作用。由于其简单性和出色的外推能力，有限温度的准粒子随机相近似（FT-QRPA）作为研究热核的性质的有效方法。 FT-QRPA中的统计合奏使该理论比其零温对应物更丰富，但也掩盖了各种物理量的含义。在这项工作中，我们阐明了FT-QRPA的几个方面，包括文献中看到的符号，并演示了如何从理论中提取物理量。为了说明对有限温度转变的正确处理，我们特别强调了质子内核FT-QRPA（FT-PNQRPA）中描述的电荷交换过渡。借助FT-PNQRPA建立在核能密度功能理论的基础上，我们使用相对论矩阵方法以及非相关的有限幅度方法获得了解决方案。我们表明，通过适当地处理来自人群的激发态的脱晶的适当处理，Ikeda和规则可以实现。此外，我们证明了这些过渡对$ {}^{58,78} $ ni的恒星电子捕获（EC）速率的影响。虽然它们的包容性不会影响$ {}^{58} $ ni的EC利率，但$ {}^{78} $ ni的费率由温度下的脱水主导。在具有较大负$ Q $ - 价值的系统中，对于在有限温度下的反应速率的完整描述中，必须在FT-QRPA内纳入脱位。
In numerous astrophysical scenarios, such as core-collapse supernovae and neutron star mergers, as in well as heavy-ion collision experiments, transitions between thermally populated nuclear excited states have been shown to play an important role. Due to its simplicity and excellent extrapolation ability, the finite-temperature quasiparticle random phase approximation (FT-QRPA) presents itself as an efficient method to study the properties of hot nuclei. The statistical ensembles in the FT-QRPA make the theory much richer than its zero-temperature counterpart, but also obscure the meaning of various physical quantities. In this work, we clarify several aspects of the FT-QRPA, including notations seen in the literature, and demonstrate how to extract physical quantities from the theory. To exemplify the correct treatment of finite-temperature transitions, we place special emphasis on the charge-exchange transitions described within the proton-neutron FT-QRPA (FT-PNQRPA). With the FT-PNQRPA built on the nuclear energy-density functional theory, we obtain solutions using a relativistic matrix approach and also the non-relativistic finite amplitude method. We show that the Ikeda sum rule is fulfilled with the proper treatment of de-excitations from thermally populated excited states. Additionally, we demonstrate the impact of these transitions on stellar electron capture (EC) rates in ${}^{58,78}$Ni. While their inclusion does not influence the EC rates in ${}^{58}$Ni, the rates in ${}^{78}$Ni are dominated by de-excitations for temperatures $T > 0.5$ MeV. In systems with a large negative $Q$-value, the inclusion of de-excitations within the FT-QRPA is necessary for a complete description of reaction rates at finite temperature.
