We reconsider the two-flavor version of the massive chiral Gross-Neveu model in $1+1$ dimensions. Its phase diagram as a function of baryon chemical potential, isospin chemical potential, and temperature has previously been explored. We recapitulate the results, adding the missing tricritical curves. They can be determined exactly by extending the standard stability analysis, using fourth-order almost degenerate perturbation theory. Results for three different bare masses are presented and discussed.

中文翻译：

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具有同旋异构体的大规模手性 Gross-Neveu 模型的三临界曲线

我们重新考虑大规模手性 Gross-Neveu 模型的两种风味版本$1+1$方面。其相图作为重子化学势、同位旋化学势和温度的函数之前已经被探索过。我们概括了结果，添加了缺失的三临界曲线。它们可以通过扩展标准稳定性分析，使用四阶几乎简并微扰理论来精确确定。给出并讨论了三种不同裸质量的结果。