We investigate the effect of screening of the four-quarks contact interactions by the ring diagram at finite temperature and density in an effective chiral model inspired by QCD in the Coulomb gauge. As a consequence, a medium-dependent coupling naturally emerges which, in a class of chiral models, brings the chiral crossover temperature down to the value calculated in lattice QCD at low net-baryon density. Furthermore, it implies a stronger divergence of the chiral susceptibility at the critical point compared to the mean-field dynamics. At high densities, the screening induces a substantial instability region and its size depends on the regularization schemes. We discuss the properties of an effective potential for a class of models described by momentum-independent gap equations. In particular, we introduce the method to construct an approximate effective potential from the gap equations to determine the location of the first-order phase transition.

中文翻译：

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四夸克相互作用动力学筛选对手性相图的影响


我们研究了在有限温度和密度下通过环图筛选四夸克接触相互作用的影响，该模型受库仑真空计中 QCD 启发的有效手性模型。因此，自然而然地出现了一个介质依赖性耦合，在一类手性模型中，手叉温度降低到在低净重子密度下晶格 QCD 中计算的值。此外，这意味着与平均场动力学相比，临界点的手性磁化率具有更强的发散性。在高密度下，筛选会引起一个相当大的不稳定区域，其大小取决于正则化方案。我们讨论了由动量无关间隙方程描述的一类模型的有效势的属性。特别是，我们介绍了从间隙方程构建近似有效电位以确定一阶相变位置的方法。