论文标题
量子场理论中的浆果阶段：恶魔点和边界现象
Berry Phase in Quantum Field Theory: Diabolical Points and Boundary Phenomena
论文作者
论文摘要
我们通过有效的现场理论研究了浆果相位的多体量子系统的各个方面。一旦将参数促进到时空依赖性背景字段，Wess-Zumino-Witten（WZW）和类似项描述了这种绝热相。在对称性的情况下，也有量化的不变式捕获通用的泵。对这些术语的考虑对多体系统的相图提供了限制，这意味着相图中存在无间隙点，这是出于拓扑原因而稳定的。我们描述了这种恶魔般的点，通过各个维度的自由费式和衡量理论实现，它们充当“较高浆果曲率”的来源，并受到相应的WZW项或无泵项的量化的保护。这些类似于半学带结构中的Weyl节点。我们认为，在边界存在的情况下，有边界的恶魔点 - 边界差距关闭的地方值---占据的弧线以大块的恶魔点结尾。因此，在Córdova等人的意义上，边界具有“耦合空间的异常”。对参数的拓扑有效作用的考虑还为2+1d中的猜想红外二元性和解还是量子关键性提供了一些新的检查。
We study aspects of Berry phase in gapped many-body quantum systems by means of effective field theory. Once the parameters are promoted to spacetime-dependent background fields, such adiabatic phases are described by Wess-Zumino-Witten (WZW) and similar terms. In the presence of symmetries, there are also quantized invariants capturing generalized Thouless pumps. Consideration of these terms provides constraints on the phase diagram of many-body systems, implying the existence of gapless points in the phase diagram which are stable for topological reasons. We describe such diabolical points, realized by free fermions and gauge theories in various dimensions, which act as sources of "higher Berry curvature" and are protected by the quantization of the corresponding WZW terms or Thouless pump terms. These are analogous to Weyl nodes in a semimetal band structure. We argue that in the presence of a boundary, there are boundary diabolical points---parameter values where the boundary gap closes---which occupy arcs ending at the bulk diabolical points. Thus the boundary has an "anomaly in the space of couplings" in the sense of Córdova et al. Consideration of the topological effective action for the parameters also provides some new checks on conjectured infrared dualities and deconfined quantum criticality in 2+1d.
