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.
Title: Mastering bounds on correlators
Abstract: We discuss a new viewpoint onto the CFT landscape: bounds on values of CFT correlators. We show that such bounds can be obtained by constructing suitable ‘master functionals’. We present both numerical results for 3d CFTs as well as exact results for correlators on the line. The latter follow from crossing symmetric dispersion relations. We briefly discuss how these may be used to study the Regge and flat space limits of CFT correlators.
Title: Multi-trace correlators in the SYK model and Non-geometric wormholes
Abstract: We consider the global fluctuations in the density of states of the SYK model, which are much larger than the standard RMT correlations. We provide a diagrammatic description of their leading and subleading behavior. In either case, the new set of correlations are not associated with (and are much larger than) the ones given by topological wormholes, and hint towards the dual of a single realization. In particular, we suggest that incorporating them in the gravity description requires the introduction of new, lighter and lighter, fields in the bulk with fluctuating boundary couplings.
Title: Bootstrapping N = 4 super-Yang-Mills on the conformal manifold
Abstract: We study the N = 4 SYM stress tensor multiplet 4-point function for any value of the complexified coupling tau, and in principle any gauge group (we focus on SU(2) and SU(3) for simplicity). By combining non-perturbative constraints from the numerical bootstrap with two exact constraints from supersymmetric localization, we are able to compute upper bounds on low-lying CFT data (e.g. the Konishi) for any value of tau. These upper bounds are very close to the 4-loop weak coupling predictions in the appropriate regime. We also give preliminary evidence that these upper bounds become small islands under reasonable assumptions, in which case our method would provide a numerical solution to N = 4 SYM for any gauge group and tau.
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.
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