Time-reversal breaking in QCD4, walls, and dualities in 2 + 1 dimensions

By D. Gaiotto, Z. Komargodski, N. Seiberg. Journal of High Energy Physics, 2017

228 citations recorded by the source corpus.

We study SU(N ) Quantum Chromodynamics (QCD) in 3+1 dimensions with Nf degenerate fundamental quarks with mass m and a θ-parameter. For generic m and θ the theory has a single gapped vacuum. However, as θ is varied through θ = π for large m there is a first order transition. For Nf = 1 the first order transition line ends at a point with a massless η′ particle (for all N ) and for Nf> 1 the first order transition ends at m = 0, where, depending on the value of Nf , the IR theory has free Nambu-Goldstone bosons, an interacting conformal field theory, or a free gauge theory. Even when the 4d bulk is smooth, domain walls and interfaces can have interesting phase transitions separating different 3d phases. These turn out to be the phases of the recently studied 3d Chern-Simons matter theories, thus relating the dynamics of QCD4 and QCD3, and, in particular, making contact with the recently discussed dualities in 2+1 dimensions. For example, when the massless 4d theory has an SU(Nf ) sigma model, the domain wall theory at low (nonzero) mass supports a 3d massless ℂℙNf−1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \mathbb{C}{\mathrm{\mathbb{P}}}^{N_f-1} $$\end{document} nonlinear σ-model with a Wess-Zumino term, in agreement with the conjectured dynamics in 2+1 dimensions.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7d3af193d346b6b63c6f34536d2ca6c264e7674c

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Citations in the corpus

Comments on one-form global symmetries and their gauging in 3d and 4d (2018, background): “It was suggested in [2, 3] that this theory is SU(N)k.”
Anomalies in the space of coupling constants and their dynamical applications II (2019, methodology): “Our analysis extends the recent results about interfaces in 4d QCD in [26] and explains the relation between them and the earlier results about anomalies in 3d Chern-Simons-matter theory in [15].”
Dai-Freed anomalies in particle physics (2018, background): “luding right handed neutrinos) is 16, which turns out to be the number of Majorana zero modes of a topological superconductor that cancels the 21This is somewhat reminiscent of a similar statement in [83,84], which nds a mixed Tavor anomaly when the number of avors is a multiple of 3, and the gauge ”