标题： 费米子-转子系统的动力学 显示英文标题

标题： Dynamics of the Fermion-Rotor System

摘要： 我们研究费米子-转子系统的动力学，这是一个在d=1+1维度中的简单杂质模型，由一组纯右行费米子组成，并与定位于原点的量子力学转子相互作用。 这是Polchinski首次提出的单极子-费米子散射的玩具模型，其表现出令人惊讶的细微之处，进入和离开的费米子携带不同的量子数。 我们表明，在低能理论中，转子充当扭转变换算符，改变之前经过原点的激发态的量子数，以确保与所有对称性一致的散射。 我们进一步展示了具有多个转子和不等电荷的该模型的推广如何被视为手征理论边界态的紫外完成，包括广泛研究的3450模型。 我们计算了进入和离开的费米子之间的关联函数，并表明与转子自由度耦合的费米子作为局部算符起作用并创建单粒子态，推广了在具有单个转子和相等电荷的理论中获得的先前结果。 最后，我们指出这些模型中存在一个模2异常，它源自4维中的Witten异常。 显示英文摘要

摘要： We explore the dynamics of the fermion-rotor system, a simple impurity model in d=1+1 dimensions that consists of a collection of purely right-moving fermions interacting with a quantum mechanical rotor localised at the origin. This was first introduced by Polchinski as a toy model for monopole-fermion scattering and is surprisingly subtle, with ingoing and outgoing fermions carrying different quantum numbers. We show that the rotor acts as a twist operator in the low-energy theory, changing the quantum numbers of excitations that have previously passed through the origin to ensure scattering consistent with all symmetries. We further show how generalisations of this model with multiple rotors and unequal charges can be viewed as a UV-completion of boundary states for chiral theories, including the well-studied 3450 model. We compute correlation functions between ingoing and outgoing fermions and show that fermions dressed with the rotor degree of freedom act as local operators and create single-particle states, generalising an earlier result obtained in a theory with a single rotor and equal charges. Finally, we point out a mod 2 anomaly in these models that descends from the Witten anomaly in 4d