论文标题
访问相关的费米系统的有序阶段：功能重新归一化组中的顶点琼脂化和平均场理论
Accessing the ordered phase of correlated Fermi systems: vertex bosonization and mean-field theory within the functional renormalization group
论文作者
论文摘要
我们提出了功能重新归一化组和均值场理论的一致融合，该理论通过临界规模明确地引入了掌位领域，以临界规模的范围内的命令转换。我们表明，流程方程的最小截断，忽略了秩序的差异，并且忽略了差异的差异，并且构成了构成的基础，这是构成的基础。全球对称性。为了介绍玻色子场，我们提出了一种技术来分解顶点最单一的部分，即使保留了对其所有论点的全部依赖。我们在半填充时在二维有吸引力的哈伯德模型上测试我们的方法，并计算超流体间隙以及Yukawa耦合以及在有序阶段的剩余两个效率相互作用，作为费米子Matsubara频率的功能。此外，我们分析了弱和中度耦合的间隙和冷凝水部分，并将我们的结果与以前的功能重新归一化组研究以及量子蒙特卡洛数据进行比较。我们的形式主义是通过保持完整的，不简化的，对费米子动量和/或频率的依赖，构成了订单参数波动的一个方便起点。
We present a consistent fusion of functional renormalization group and mean-field theory which explicitly introduces a bosonic field via a Hubbard-Stratonovich transformation at the critical scale, at which the order sets in. We show that a minimal truncation of the flow equations, that neglects order parameter fluctuations, is integrable and fulfills fundamental constraints as the Goldstone theorem and the Ward identity connected with the broken global symmetry. To introduce the bosonic field, we present a technique to factorize the most singular part of the vertex, even when the full dependence on all its arguments is retained. We test our method on the two-dimensional attractive Hubbard model at half-filling and calculate the superfluid gap as well as the Yukawa couplings and residual two fermion interactions in the ordered phase as functions of fermionic Matsubara frequencies. Furthermore, we analyze the gap and the condensate fraction for weak and moderate couplings and compare our results with previous functional renormalization group studies, and with quantum Monte Carlo data. Our formalism constitutes a convenient starting point for the inclusion of order parameter fluctuations by keeping a full, non simplified, dependence on fermionic momenta and/or frequencies.
