We analyze the features of strongly interacting matter in the presence of nonzero isospin chemical potential ${\mu }_I$, within a nonlocal two-flavor Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model. For a system at finite temperature $T$, we describe the behavior of various thermodynamic quantities and study the phase diagram in the ${\mu }_I-T$ plane. In particular, it is found that for values of ${\mu }_I$ larger than the pion mass and temperatures lower than a critical value of about 170 MeV the system lies in an isospin symmetry broken phase signalled by the presence of a nonzero pion condensate. Our results for the phase diagram are found to be in better agreement with those arising from lattice QCD calculations, as compared to the predictions from other theoretical approaches like the local PNJL model.

中文翻译：

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非局域手性夸克模型中的同位旋非对称物质

我们分析了在非零同位旋化学势存在下强相互作用物质的特征 ${\mu }_{\mathrm{一世}}$，在非局部的两种风味 Polyakov 环扩展的 Nambu-Jona-Lasinio (PNJL) 模型中。对于有限温度系统$吨$，我们描述了各种热力学量的行为并研究了相图 ${\mu }_{\mathrm{一世}}-吨$飞机。特别地，发现对于值${\mu }_{\mathrm{一世}}$当大于 pion 质量且温度低于约 170 MeV 的临界值时，系统处于同位旋对称性破相，由非零 pion 凝聚物的存在发出信号。与其他理论方法（如局部 PNJL 模型）的预测相比，我们发现相图的结果与晶格 QCD 计算得出的结果更一致。