Cambridge High Energy Workshop 2021 - Axion Physics

Session

Session 5

29 Jul 2021, 09:00

Zoom / Gather.town

27. Peeking into the theta vacuum of 4d SU(2) Yang-Mills theory

Norikazu Yamada (KEK)

29/07/2021, 09:00

We propose a subvolume method to study the $\theta$ dependence of the free energy density of the four-dimensional SU($N$) Yang-Mills theory on the lattice. As an attempt, the method is first applied to SU(2) Yang-Mills theory at $T=1.2\,T_c$ to understand the systematics of the method. We then proceed to the calculation of the vacuum energy density and obtain the $\theta$ dependence, at...

39. Fermions as "axion" strings in a monopole background

Ryutaro Matsudo (KEK Theory Center)

29/07/2021, 09:30

In the monopole background, multi-fermion operators exhibit condensation. The phases of the operators are "axions" in the sense that they are topologically coupled to the electromagnetic field. We propose that an ``excited'' closed axion string is the fermion itself. We use this picture to solve a long-standing puzzle in the scattering process of a monopole and a massless fermion. It has been...

24. Axions, Higher-Groups, and Emergent Symmetry

T Daniel Brennan (University of Chicago)

29/07/2021, 10:00

Axion models are phenomenologically relevant QFTs that exhibit higher group global symmetries. Higher groups describe the case when different types of higher form symmetries combine together in a non-trivial structure. In this talk, we will discuss how the emergence of these higher groups can be used to infer non-trivial constraints on the RG flows of theories that flow to axion-Yang-Mills in the IR.