When a strongly correlated system supports well-defined quasiparticles, it allows for an elegant one-body effective description within the non-Hermitian topological theory. While the microscopic many-body Hamiltonian of a closed system remains Hermitian, the one-body quasiparticle Hamiltonian is non-Hermitian due to the finite quasiparticle lifetime. We use such a non-Hermitian description in the heavy-fermion two-dimensional systems with the momentum-dependent hybridization to reveal a fascinating phenomenon which can be directly probed by the spectroscopic measurements, the bulk “Fermi arcs.” Starting from a simple two-band model, we first combine the phenomenological approach with the perturbation theory to show the existence of the Fermi arcs and reveal their connection to the topological exceptional points, special points in the Brillouin zone where the Hamiltonian is nondiagonalizable. The appearance of such points necessarily requires that the electrons belonging to different orbitals have different lifetimes. This requirement is naturally satisfied in the heavy-fermion systems, where the itinerant $c$ electrons experience much weaker interaction than the localized $f$ electrons. We then utilize the dynamical mean field theory to numerically calculate the spectral function and confirm our findings. We show that the concept of the exceptional points in the non-Hermitian quasiparticle Hamiltonians is a powerful tool for predicting new phenomena in strongly correlated electron systems.

中文翻译：

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DMFT揭示了重型费米子系统中的非埃尔米特拓扑和费米弧

当高度相关的系统支持定义明确的拟粒子时，它可以在非Hermitian拓扑理论内进行优雅的单体有效描述。虽然封闭系统的微观多体哈密顿量仍为埃尔米特，但由于有限的准颗粒寿命，单体准粒子哈密顿量不是非埃尔米特数。我们在重费米子二维系统中使用这种非Hermitian的描述，并具有动量依赖性杂交，以揭示一种引人入胜的现象，该现象可以通过光谱测量直接检测到，即“费米弧”。我们从简单的两波段模型开始，首先将现象学方法与微扰理论相结合，以显示费米弧的存在，并揭示它们与拓扑例外点的联系，哈密​​顿量不可对角化的布里渊区中的特殊点。这些点的出现必然要求属于不同轨道的电子具有不同的寿命。在重费米子系统中，流动性自然满足了这一要求$C$ 电子所经历的相互作用比局部电子弱得多 $F$电子。然后，我们利用动态平均场理论来数值计算频谱函数并确认我们的发现。我们表明，非埃尔米特准粒子哈密顿量中例外点的概念是预测强相关电子系统中新现象的有力工具。