热核系统中质子-中子配对的重入现象
Reentrance of proton-neutron pairing in hot nuclear systems
- Duy Tan University（越南科技大学）
- Joint Institute for Nuclear Research（俄罗斯联合核研究所）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文提出有限温度质子-中子BCS框架，发现偶偶非对称核中pn配对重入现象，由热解阻塞与同类核子配对相互作用引起，可能影响恒星弱相互作用速率。
AI中文摘要：
我们利用超算符形式体系发展了一个广义的有限温度质子-中子BCS框架，该框架同时包含同位旋矢量和同位旋标量单极配对通道。针对一个示意性的等距多能级模型以及现实的偶偶Ge同位素的数值计算表明，在预先存在同类核子配对关联的偶偶非对称（N>Z）原子核中，会出现质子-中子（pn）配对重入现象。这种非单调行为源于热激发部分解除了化学势附近单粒子轨道的泡利阻塞，从而扩大了pn对形成的相空间。我们揭示了热解阻塞与同类核子配对之间微妙的相互作用，这种相互作用根据温度和壳层填充情况可以抑制或增强pn关联。对热$^{72}$Ge中费米电荷交换强度函数的定性分析（该分析忽略了热准粒子之间的剩余相互作用）表明，pn配对重入可能在$T\approx1$~MeV附近改变跃迁强度分布。这表明有限温度的pn关联可能潜在地影响$rp$过程和超新星环境中的恒星弱相互作用速率。
英文摘要：
We develop a generalized finite-temperature proton-neutron BCS framework using the superoperator formalism, incorporating both isovector and isoscalar monopole pairing channels. Numerical calculations for a schematic equidistant multilevel model and realistic even-even Ge isotopes demonstrate the emergence of proton-neutron ($pn$) pairing reentrance in even-even asymmetric ($N>Z$) nuclei with preexisting like-nucleon pairing correlations. This nonmonotonic behavior arises from thermal excitations that partially lift Pauli blocking of single-particle orbitals near the chemical potentials, thereby enlarging the phase space for $pn$ pair formation. We uncover a delicate interplay between thermal unblocking and like-nucleon pairing, which can either suppress or enhance $pn$ correlations depending on temperature and shell filling. A qualitative analysis of Fermi charge-exchange strength functions in hot $^{72}$Ge, which neglects the residual interaction between thermal quasiparticles, suggests that $pn$ pairing reentrance may alter the transition strength distribution around $T\approx1$~MeV. This indicates that finite-temperature $pn$ correlations could potentially impact stellar weak-interaction rates in $rp$-process and supernova environments.
