Talk by Professor Zohar Komargodski, SCGP, Stony Brook University, New York at QASTM seminar
Channel: Sayantan Choudhury
Date: 2020-05-18

Title: The High-Temperature Limit of QFT 

Based on his recent work "Thermal Order in Conformal Theories" Ref:https://arxiv.org/abs/2005.03676

Abstract:

It is widely expected that at sufficiently high temperatures order is always lost, e.g. magnets loose their ferromagnetic properties. We pose the question of whether this is always the case in the context of quantum field theory in d space dimensions. More concretely, one can ask whether there exist critical points in CFTs which break some global symmetry at arbitrary finite temperature. The most familiar CFTs do not exhibit symmetry breaking at finite temperature, and moreover, in the context of the AdS/CFT correspondence, critical points at finite temperature are described by an uncharged black brane which obeys a no-hair theorem. Yet, we show that there exist CFTs which have some of their internal symmetries broken at arbitrary finite temperature. Our main example is a vector model which we study both in the epsilon expansion and arbitrary rank as well as the large rank limit and arbitrary dimension. The large rank limit of the vector model displays a conformal manifold, a moduli space of vacua, and a deformed moduli space of vacua at finite temperature. The appropriate Nambu-Goldstone bosons including the dilaton-like particle are identified. Using these tools we establish symmetry breaking at finite temperature for finite small. We also prove that a large class of other fixed points, which describe some of the most common quantum magnets, indeed behave as expected and do not break any global symmetry at finite temperature. We discuss some of the consequences of finite temperature symmetry breaking for the spectrum of local operators. Finally, we propose a class of fixed points which appear to be possible candidates for finite temperature symmetry breaking in d = 2.

Speaker: Professor Zohar Komargodski, Simons Center for Geometry and Physics, Stony Brook University, New York, USA 

Time: 18:00 pm to 19:30 pm

Date: 18 th May 2020.

Biodata of Professor Zohar Komargodski:

Zohar joins the SCGP from the Weizmann Institute of Science, Department of Particle Physics and Astrophysics, in Rehovot Israel, where he held the position of Associate Professor. He received his Ph.D. from the Weizmann Institute in Physics in 2008, after which he served as a postdoctoral fellow at the Institute for Advanced Study. His research studies in theoretical particle physics include a variety of topics such as Quantum Field Theory, Conformal Symmetry, Supersymmetry, Quantum Gravity, and Particle Physics Phenomenology. Zohar has proven to be a bright and emerging young physicist and has been awarded many prizes including the New Horizons in Physics Prize as part of the Fundamental Physics Prize Foundation, in 2012, the Gribov Medal for outstanding work by a young physicist in Theoretical Particle Physics and/or Field Theory, in 2013, and the Philippe Meyer Prize in Theoretical Physics in 2014.