探索NJL模型中磁场下由介子屏蔽质量揭示的$U_A(1)$对称性恢复

中文摘要 AI 辅助

我们在$(2+1)$味Nambu-Jona-Lasinio（NJL）模型中，利用介子屏蔽质量以及介子磁化率，研究了有限温度和外磁场下有效轴向$U_A(1)$对称性的恢复。为了纳入逆磁催化效应，我们采用了由格点QCD手征赝临界温度约束的磁场依赖的四夸克耦合，并固定't Hooft耦合。在格点改进的NJL模型中，$U_A(1)$伙伴$\delta^0$和$\pi^0$之间的纵向屏蔽质量差及其归一化介子磁化率差在低温下表现出轴向磁催化，在手征交叉附近表现出轴向逆磁催化，而横向屏蔽质量差在所有温度下均随$eB$增大而增加。尽管存在这些不同的响应，从这三个替代序参量的热拐点提取的轴向赝临界温度均随$eB$减小，这意味着在固定温度下，赝临界温度的降低可以与横向屏蔽质量差的增加共存。

英文摘要

We investigate the effective axial $U_A(1)$ symmetry restoration at finite temperature in an external magnetic field using meson screening masses, as well as meson susceptibilities, in a $(2+1)$-flavor Nambu-Jona-Lasinio (NJL) model. To incorporate inverse magnetic catalysis, we employ a magnetic-field-dependent four-quark coupling constrained by the lattice QCD chiral pseudo-critical temperature, with the 't Hooft coupling fixed. In the lattice-improved NJL model, the longitudinal screening mass difference between the $U_A(1)$ partners $δ^0$ and $π^0$ and their normalized meson susceptibility difference exhibit axial magnetic catalysis at low temperatures and axial inverse magnetic catalysis near the chiral crossover, whereas the transverse screening mass difference increases with $eB$ at all temperatures. Despite these different responses, the axial pseudo-critical temperatures extracted from the thermal inflection points of these three alternative order parameters decrease with $eB$, implying that a decreasing pseudo-critical temperature can coexist with an increasing transverse screening mass difference at fixed temperature.

发表机构

• College of Physics, Jilin University（吉林大学物理学院）
• School of Physical Science and Technology, Inner Mongolia University（内蒙古大学物理科学与技术学院）
• Center for Fundamental Physics, School of Mechanics and Optoelectronic Physics, Anhui University of Science and Technology（安徽理工大学力学与光电物理学院基础物理中心）
• Department of Physics and Siyuan Laboratory, Jinan University（暨南大学物理系思言实验室）

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