BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Zohar Komargodski (Simons Center for Geometry and Physics\, Stony Brook University (SUNY Stony Brook)\, New York\, USA) DTSTART:20200518T160000Z DTEND:20200518T173000Z DTSTAMP:20260423T010920Z UID:QASTM/3 DESCRIPTION:Title: Th ermal order in conformal theories\nby Zohar Komargodski (Simons Center for Geometry and Physics\, Stony Brook University (SUNY Stony Brook)\, Ne w York\, USA) as part of Quantum Aspects of Space-Time and Matter\n\n\nAbs tract\nIt is widely expected that at sufficiently high temperatures order is always lost\, e.g. magnets loose their ferromagnetic properties. We pos e the question of whether this is always the case in the context of quantu m field theory in d space dimensions. More concretely\, one can ask whethe r there exist critical points (CFTs) which break some global symmetry at a rbitrary finite temperature. The most familiar CFTs do not exhibit symmetr y breaking at finite temperature\, and moreover\, in the context of the Ad S/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 l arge rank limit (and arbitrary dimension). The large rank limit of the vec tor model displays a conformal manifold\, a moduli space of vacua\, and a deformed moduli space of vacua at finite temperature. The appropriate Namb u-Goldstone bosons including the dilaton-like particle are identified. Usi ng these tools we establish symmetry breaking at finite temperature for fi nite small ϵ. We also prove that a large class of other fixed points\, wh ich describe some of the most common quantum magnets\, indeed behave as ex pected and do not break any global symmetry at finite temperature. We disc uss some of the consequences of finite temperature symmetry breaking for t he spectrum of local operators. Finally\, we propose a class of fixed poin ts which appear to be possible candidates for finite temperature symmetry breaking in d=2.\n LOCATION:https://researchseminars.org/talk/QASTM/3/ END:VEVENT END:VCALENDAR