arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2005.11314hep-thcond-mat.str-el
收藏

费米子的边界RG流和Mod 2 Anomaly

Boundary RG Flows for Fermions and the Mod 2 Anomaly

Philip Boyle Smith, David Tong

摘要:

在d=1+1维的马约拉纳费米子的边界条件落入两个SPT阶段之一,与模2异常。在这里,我们考虑2N马约拉纳费米子保持$U(1)^N$对称性的边界条件。一般来说,在这种对称性下,向左运动和向右运动的费米子携带不同的电荷,边界条件的实现需要新的自由度,这在边界中心荷$g$中表现出来。我们遵循的边界RG流诱导打开相关的边界运营商。我们确定了红外边界态。在许多情况下,边界状态翻转SPT类,导致需要消除异常的紧急马约拉纳模式。我们证明了UV和IR边界中心荷的比值由扰动边界算子的维数$g^2_{IR} / g^2_{UV} = {\rm dim}\,({\cal O})$给出。任何相关的算子必然具有${\rm dim}({\cal O}) < 1$,确保中心荷按照g-定理减少。

英文摘要:

Boundary conditions for Majorana fermions in d=1+1 dimensions fall into one of two SPT phases, associated to a mod 2 anomaly. Here we consider boundary conditions for 2N Majorana fermions that preserve a $U(1)^N$ symmetry. In general, the left-moving and right-moving fermions carry different charges under this symmetry, and implementation of the boundary condition requires new degrees of freedom, which manifest themselves in a boundary central charge, $g$. We follow the boundary RG flow induced by turning on relevant boundary operators. We identify the infra-red boundary state. In many cases, the boundary state flips SPT class, resulting in an emergent Majorana mode needed to cancel the anomaly. We show that the ratio of UV and IR boundary central charges is given by $g^2_{IR} / g^2_{UV} = {\rm dim}\,({\cal O})$, the dimension of the perturbing boundary operator. Any relevant operator necessarily has ${\rm dim}({\cal O}) < 1$, ensuring that the central charge decreases in accord with the g-theorem.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑