慶應義塾大学 · 物理学・天文学
Ryo Yokokura教授の研究室では、4次元の量子場理論における高次対称性(高次フォーム対称性)と高次群構造の解明を主眼としています。特に、axion電磁力学やトポロジカル場理論における非可逆的対称性や3群・4群構造の出現、それらがもたらす物理的効果(例:分数電荷の誘起、タイプ-B対称性の spontaneously broken)を、相関関数や双対変換の手法を用いて分析しています。また、トポロジカル秩序やインスタビリティのメカニズムについても、電場に起因する一般化されたキラル不安定性など、新しい視点から探求しています。
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We study higher-form symmetries in a low-energy effective theory of a massless axion coupled with a photon in (3+1) dimensions. It is shown that the higher-form symmetries of this system are accompanied by a semistrict 3-group (2-crossed module) structure, which can be found by the correlation functions of symmetry generators of the higher-form symmetries. We argue that the Witten effect and anomalous Hall effect in the axion electrodynamics can be described in terms of 3-group transformations.
We study higher-form global symmetries and a higher-group structure of a low-energy limit of $(3+1)$-dimensional axion electrodynamics in a gapped phase described by a topological action. We argue that the higher-form symmetries should have a semi-strict 4-group (3-crossed module) structure by consistency conditions of couplings of the topological action to background gauge fields for the higher-form symmetries. We find possible 't Hooft anomalies for the 4-group global symmetry, and discuss phy
We study non-invertible global symmetries in $(3+1)$-dimensional axion electrodynamics with a massless axion and a massless photon. In addition to a previously known non-invertible 0-form shift symmetry of the axion, we find a non-invertible 1-form symmetry associated with the equation of motion for the photon. Correlation functions of non-invertible symmetry defects lead to invertible 1- and 2-form symmetry defects associated with Bianchi identities for the axion and photon. In terms of the cor
We show that axion models with the domain wall number k in (3+1) dimensions, i.e., periodic scalar field theories admitting k axion domain walls, exhibit an emergent Zk 3-form symmetry for k>1 in addition to a conventional Zk 0-form symmetry. The emergent 3-form symmetry is explicitly shown by establishing a low-energy dual transformation between the scalar field theory and a 3-form gauge theory. We further argue that the emergent 3-form symmetry is spontaneously broken, and the breaking pattern
A bstract We demonstrate a universal mechanism of a class of instabilities in infrared regions for massless Abelian p -form gauge theories with topological interactions, which we call generalized chiral instabilities. Such instabilities occur in the presence of initial electric fields for the p -form gauge fields. We show that the dynamically generated magnetic fields tend to decrease the initial electric fields and result in configurations with linking numbers, which can be characterized by non
We study higher-form symmetries and a higher group in the low energy limit of a (3+1)-dimensional axion electrodynamics with a massive axion and a massive photon. A topological field theory describing topological excitations with the axion-photon coupling, which we call a topological axion electrodynamics, is obtained in the low energy limit. Higher-form symmetries of the topological axion electrodynamics are specified by equations of motion and Bianchi identities. We find that there are induced
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