标题： QCD相图在$T-eB$平面中对于不同介子质量的情况 显示英文标题

标题： QCD phase diagram in the $T-eB$ plane for varying pion mass

摘要： 我们研究了变化的介子质量在存在外部磁场的情况下对量子色动力学(QCD)相图的影响，旨在首次使用Nambu\textendash Jona-Lasinio类似的有效模型来理解它。 我们比较了其局部版本和非局部版本的结果。 在两种情况下，我们都发现随着介子质量的增加，交叉区域附近的反磁催化（IMC）效应被消除，而随着磁场增加交叉温度的下降趋势对于至少达到$440$ MeV的介子质量值仍然存在。 因此，这些模型能够定性地捕捉到格点QCD（LQCD）对于重（不现实的）介子所找到的结果。 模型的关键特征是引入了随着能量增加耦合常数减少的影响。 除了再现IMC效应外，它还使模型能够在不引入额外参数的情况下描述更重的当前夸克质量的影响。 对于局部NJL模型，这种一致性取决于模型在物理点处参数的拟合方式。 在这方面，由于其表述方式，非局部版本在交叉区域自动表现出IMC效应，从而更自然地捕捉物理现象。 我们进一步使用非局部框架来确定介子质量的阈值，超过该阈值后，转变区域附近的IMC效应将不再存在。 显示英文摘要

摘要： We study the effect of a varying pion mass on the quantum chromodynamics (QCD) phase diagram in the presence of an external magnetic field, aiming to understand it, for the first time, using Nambu\textendash Jona-Lasinio like effective models. We compare results from both its local and nonlocal versions. In both cases, we find that the inverse magnetic catalysis (IMC) near the crossover is eliminated with increasing pion mass, while the decreasing trend of crossover temperature with increasing magnetic field persists for pion mass values at least up to $440$ MeV. Thus, the models are capable of capturing qualitatively the results found by lattice QCD (LQCD) for heavy (unphysical) pions. The key feature in the models is the incorporation of the effect of a reduction in the coupling constant with increasing energy. Along with reproducing the IMC effect, it enables models to describe the effects of heavier current quark masses without introducing additional parameters. For the local NJL model, this agreement depends on how the parameters of the model are fit at the physical point. In this respect, the nonlocal version, which, due to its formulation, automatically exhibits the IMC effect around the crossover region, captures the physics more naturally. We further use the nonlocal framework to determine the pion mass beyond which the IMC effect around the transition region does not exist anymore.