Events Archive

HET Seminar | Igor Klebanov, Princeton University | "Tensor Models and Melonic Large N Limits"
Mon, Jan 30, 2017, 2:30 pm2:30 pm

We review the double line notation for the Feynman diagram expansion of N by N matrix models. In the ‘t Hooft large N limit only the planar diagrams survive, and the dual graphs may be thought of as discretized random surfaces. We proceed to theories where the dynamical degrees of freedom are rank-3 tensors with distinguishable indices, each of…

HET Seminar | Anton Kapustin, California Institute of Technology | "Bosonization in Two and Three Dimensions and Spin Structures”
Mon, Dec 12, 2016, 2:30 pmWed, Dec 7, 2016, 3:30 pm
I will explain in examples how to incroporate the dependence on spin structure in fermionic lattice models. In two dimensions, I show to construct a spin-TQFT out of a superalgebra. In three dimensions, it turns out that fermionic lattice models are related to bosonic models with a global 1-form symmetry. This bosonization statement can be used…
HET Seminar | Raffaele D'Agnolo, Member, School of Natural Sciences, IAS | "WIMPs, Miracles and Coincidences"
Fri, Dec 9, 2016, 1:45 pm2:45 pm
I will briefly review our current experimental knowledge of dark matter and then discuss recent developments in model building. In particular I will show that dark matter can be a thermal relic exponentially lighter than the weak scale without being exponentially weakly coupled. I will discuss concrete examples of light thermal dark matter with…
HET Seminar | Steve Gubser, Princeton University | "p-adic AdS/CFT"
Fri, Dec 2, 2016, 1:45 pm2:45 pm
I will give a first-principles introduction to p-adic numbers and p-adic AdS/CFT. p-adic numbers are an alternative to the real numbers, and they have a hierarchical structure which lends itself naturally to a holographic construction. The bulk dual to a p-adic boundary is the so-called Bruhat-Tits tree, an infinite regular graph. A bulk…
HET Seminar | Igal Arav, Tel Aviv University | "Non-Relativistic Scale Anomalies and Geometry"
Tue, Nov 29, 2016, 1:30 pm2:30 pm
I will discuss the coupling of non-relativistic field theories to curved spacetime, and develop a framework for analyzing the possible structure of non-relativistic (Lifshitz) scale anomalies using a cohomological formulation of the Wess-Zumino consistency condition. I will compare between cases with or without Galilean boost symmetry, and…
HET Seminar | Jaume Gomis, Perimeter Institute | “Correlation Functions in Superconformal Field Theories”
Mon, Nov 28, 2016, 2:30 pm3:30 pm
We discuss the exact determination of correlation functions of local operators in four-dimensional N=2 superconformal field theories.

HET Seminar | Bogdan Stoica, Brandeis University | "Tensor networks, p-adic fields, and algebraic curves: arithmetic and the AdS3/CFT2 correspondence"
Mon, Nov 21, 2016, 2:30 pm3:30 pm
One of the many remarkable properties of conformal field theory in two dimensions is its connection to algebraic geometry. Since every compact Riemann surface is a projective algebraic curve, many constructions of interest in physics (which a priori depend on the analytic structure of the spacetime) can be formulated in purely algebraic language…
Senthil Todadri, Massachusetts Institute of Technology - "Symmetry Enriched Emergent U(1) Gauge Theories"
Mon, Nov 14, 2016, 2:30 pm4:00 pm
Phases of quantum many particle systems can have low energy effective field theoretic descriptions in terms of gauge theories in their deconfined phase. Such emergent gauge theories play a central role in modern theoretical work in condensed matter physics. In the presence of global symmetry many such phases - with the same emergent gauge…
HET Seminar | Senthil Todadri, Massachusetts Institute of Technology | “Symmetry Enriched Emergent U(1) Gauge Theories"
Mon, Nov 14, 2016, 2:30 pm3:30 pm
Phases of quantum many particle systems can have low energy effective field theoretic descriptions in terms of gauge theories in their deconfined phase. Such emergent gauge theories play a central role in modern theoretical work in condensed matter physics. In the presence of global symmetry many such phases - with the same emergent gauge…
HET Seminar | Thomas Mertens, Princeton University | “An Investigation of AdS2 Backreaction and Holography"
Fri, Nov 11, 2016, 1:45 pm3:00 pm
In this talk, I will discuss the Jackiw-Teitelboim model in 2d dilaton gravity in a holographic context. After deriving the boundary time reparametrization equation and the holographic stress tensor, I will demonstrate that these can be obtained from an effective boundary model. Within that description, the commutator of matter fields at large…
HET Seminar | Daniel Park, Rutgers University | "Towards Finding All Elliptically Fibered Calabi-Yau Threefolds"
Mon, Nov 7, 2016, 2:30 pm3:30 pm
I will review the efforts made towards approaching string universality in six dimensions and report recent "cartographic" developments on exploring the landscape of six-dimensional string vacua. A working conjecture is that all six-dimensional string vacua can be constructed in F-theory, which leads to the problem of classifying all elliptically…
HET Seminar | Xi Dong, Member, School of Natural Sciences, IAS | "The Ryu-Takayanagi Formula and Extremal Surfaces”
Fri, Nov 4, 2016, 1:45 pm2:45 pm
The Ryu-Takayanagi formula and its quantum-corrected version are useful in understanding many aspects of quantum gravity such as subregion duality, emergence of the radial direction, and the generalized second law. In this talk, I will first present a classical argument showing that in the large N limit the von Neumann entropy of a boundary…
HET Seminar | Ellis Ye Yuan, School of Natural Sciences, IAS | “Projective Geometry of Scattering Amplitudes”
Fri, Oct 28, 2016, 1:45 pm2:45 pm
I will introduce a technique in studying the analytic structure of perturbative S-matrix of QFTs. The main idea is to associate Feynman integrals to objects in a projective space: polytopes and hypersurfaces. At one loop, this reveals a universal structure for all possible Feynman integrals (in particular, including one-loop amplitudes in any…
HET Seminar | Alba Grassi, ICTP in Trieste | "Topological string, spectral theory and Painlevé equations"
Mon, Oct 24, 2016, 2:30 pm3:30 pm
In this talk I will review some aspects of a recently proposed duality between topological string on toric Calabi-Yau manifolds and the spectral theory of trace class operators. I will discuss the relation between this construction and Painlevé equations which can be used to prove the duality in a 4-dimensional limit. In addition I will apply…
Subir Sachdev, Harvard University, "Strange Metals, Black Holes, and Graphene”
Mon, Oct 17, 2016, 2:30 pmTue, Oct 11, 2016, 3:30 pm
States of quantum matter without quasiparticles can be more precisely characterized by their rapid approach to local thermal equilibrium: this is argued to happen in a shortest possible time of order (Planck’s constant)/((Boltmann’s constant)x(absolute temperature)). Black holes are physical systems which also equilibrate in this time, with the…
HET/IAS Seminar | Subir Sachdev, Harvard University | “Strange Metals, Black Holes, and Graphene”
Mon, Oct 17, 2016, 2:30 pm3:30 pm
States of quantum matter without quasiparticles can be more precisely characterized by their rapid approach to local thermal equilibrium: this is argued to happen in a shortest possible time of order (Planck’s constant)/((Boltmann’s constant)x(absolute temperature)). Black holes are physical systems which also equilibrate in this time, with the…
Francesco Benini, Junior Faculty Member, School of Natural Sciences, IAS; SISSA (Trieste), “AdS Black Hole Entropy and Gauge Theory”
Fri, Oct 14, 2016, 1:45 pmTue, Oct 11, 2016, 3:00 pm
I will discuss how to relate the entropy of BPSblack holes in AdS to counting of states in gaugetheory, presenting examples where this can besuccessfully done as well as examples where thisdoes not seem to work.