During the semester we have a high energy seminar and a lunch seminar. In addition to these two seminars we participate in a joint theoretical high energy theory seminar in Newe Shalom. The joint seminar takes place on Tuesdays from 10:30 until 13:30 and includes two talks and lunch. This seminar is attended by the high energy groups of all the Israeli institutions and usually attracts a crowd of roughly twenty participants.

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**Title: **Thermal Order in 3d

**Abstract: **Our intuitive understanding of thermodynamics suggests that broken global symmetries in the stable vacuum of a physical system, get restored at high temperatures. We construct a unitary, UV-complete 3d QFT that instead exhibits a spontaneous breaking of continuous symmetries at all temperatures. Our model consists of two copies of the long-range vector model, with O(m) and O(N−m) global symmetry groups, perturbed by double-trace deformations. The model exhibits a conformal manifold in the large rank limit, that is lifted by 1/N corrections. A certain class of IR fixed points are shown to undergo SSB at finite temperature, with the pattern persisting to all temperatures due to scale-invariance. We provide evidence that the models in question are unitary, UV-complete, as well as invariant under conformal symmetry. Our work adds to the growing list of models that display persistent symmetry breaking (PSB), and discusses the necessary conditions for the models to display such a behaviour.

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**Title: **Conformal operators in SYK-like models and their numerical effects

**Abstract: **Quantum mechanical models with random interactions have an infinite number of bilinear operators, the scaling dimensions of which can be computed explicitly in the large N limit. The lowest dimension operators play an important role in thermodynamical properties of these models and define the behavior of various correlation functions in the infrared limit. In this talk I’ll show that some SYK-like models have operators with unusual anomalous dimensions. I also demonstrate how they can be observed in numerical computations.

Based on works with Maria Tikhanovskaya, Haoyu Guo and Subir Sachdev

https://arxiv.org/abs/2010.09742

https://arxiv.org/abs/2012.14449

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**Title:** Magnetic Quivers, Phase Diagrams, and Physics at Strongly Coupled Quantum Field Theories

**Abstract:** Quiver gauge theories experienced a breakthrough in activity through two important concepts, called “magnetic quivers” and “Hasse (phase) diagrams”. The first helps understanding the physics of strongly coupled gauge theories and exotic theories with tensionless strings in 6d or with massless gauge instants in 5d. The second gives an invaluable information about the phase structure of gauge theories, in analogy with phases of water. The talk will review these developments and explain their significance.

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** Title: **Some aspects of line defects in d dimensions

** Abstract:** We consider renormalization group flows on line defects in d dimensions. We define a “defect entropy” and argue that it decreases monotonically during RG flows. We apply this result to line defects which appear in condensed matter and high energy physics, including magnetic (SPT) defects, localized field defects, and Wilson loops. In some of these cases we make some new experimental predictions and in the case of Wilson lines we make some comparisons with localization and holography.

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