Events Archive

High Energy Theory Seminar - Mykola Dedushenko, Princeton University - "Chiral algebras in 2d N=(0,2) theories"
Fri, Feb 26, 2016, 1:45 pm3:00 pm
A supersymmetric sector of N=(0,2) theories in two dimensions defined by taking the cohomology of one of the supercharges is known to carry the structure of a chiral algebra. I will talk about some general and more concrete properties of such algebras. Based on supersymmetry only, it is possible to argue that this algebra is an RG-invariant…
Physics Group Meeting IAS - Discussion Group led by Mauricio Romo, IAS - “Gauged Linear Sigma Models, B-branes and Hemispheres”
Wed, Feb 24, 2016, 1:30 pm2:30 pm
I'll start reviewing some aspects of my paper with K. Hori [1] about localization of Gauged Linear Sigma Models (GLSM) on a disc/hemisphere. The focus is on a special class of boundary conditions corresponding to B-branes. I'll then review the relevant concept of grade restriction rule [2] which is fundamental for transport of B-branes around the…
High Energy Theory - Wilke van der Schee, MIT - "Evolution of the jet opening angle distribution in holographic plasma"
Mon, Feb 22, 2016, 2:30 pm3:30 pm
Jets are particularly interesting probes to study the formation and evolution of quark-gluon plasma, as created in heavy ion collisions. In this talk I will briefly review attempts to describe the jet evolution in holography, and will argue that essential progress can be made by studying also the substructure of the jet, in particular the…
High Energy Theory Seminar IAS - Carlos Mafra, IAS - "Multiloop Scattering Amplitudes in String and Field Theory"
Fri, Feb 19, 2016, 1:45 pm3:00 pm
I will review recent progress in the computation of multiloopscattering amplitudes using the pure spinor formalism of the superstring and make comments about future directions.

Physics Group Meeting IAS - Discussion Group Led by Jennifer Lin, Member, IAS - TBA
Wed, Feb 17, 2016, 1:30 pm2:30 pm
I would like to discuss the idea that CFT entanglement explains gravity in AdS/CFT. van Raamsdonk et al. [1] showed that the linearized Einstein equations about the AdS vacuum are equivalent to the entanglement first law in CFT’s, assuming the Ryu-Takayanagi formula. We would like to understand if this argument can be extended to all horizonless…
High Energy Theory Seminar - Aitor Lewkowycs, Princeton University - "Modular hamiltonians and relative entropies for holographic states"
Fri, Feb 12, 2016, 1:45 pm3:00 pm
In this talk, we will use the holographic entanglement entropy formulas to derive a simple expression for the modular hamiltonian in bulk perturbation theory, for an arbitrary state and subregion. This remarkably simple expression has interesting properties such as the equality of bulk and boundary modular flow and relative entropy, to leading…
High Energy Theory - John Gracey, University of Liverpool - "Higher dimensional quantum field theories - old methods for the modern arena"
Mon, Feb 8, 2016, 2:30 pm3:30 pm
We review recent results of the renormalization group functions of scalar quantum field theories in various spacetime dimensions and their application to recent ideas in conformal field theories as a prelude to the extension to gauge theories. At the outset we concentrate on six dimensional phi^3 theory and briefly discuss and update its…
High Energy Theory Seminar IAS - Ellis Ye Yuan, IAS - “Tree and One-Loop Amplitudes from Scattering Equations”
Fri, Feb 5, 2016, 1:45 pm3:00 pm
Scattering equations are useful in organizing perturbative S-matrix of massless particles. Based on these equations tree-level amplitudes admit a compact expression in theories such as pure Yang-Mills, gravity, etc, where properties such as unitarity and gauge invariance almost come for free. After reviewing the tree-level construction, I will…
Physics Group Meeting - IAS - Discussion group led by Nima Arkani-Hamed, IAS - “The Diphoton Excess and Physics Beyond the Standard Model”
Wed, Feb 3, 2016, 1:30 pm2:30 pm
Assuming the diphoton excess at 750 GeV is real (a bigassumption!), we will have a discussion of various theoreticalpossibilities for what the underlying physics might be. Some refs are 1512.04933, 1512.07904, 1512.07733

High Energy Theory Seminar IAS - Marcus Spradlin, Brown University, "Landau Singularities and Symbology”
Mon, Feb 1, 2016, 2:30 pm3:30 pm
In previous work it has been observed that the singularitystructure of multi-loop scattering amplitudes in planar N=4super-Yang-Mills theory is evidently dictated by cluster algebras. In my talk I will discuss the interplay between this mathematical observation and the physical principle that the singularities of Feynman integrals are encoded in…
High Energy Theory IAS - Matthew Low, IAS - “Possibilities for the 750 GeV Excess”
Fri, Jan 22, 2016, 1:45 pm3:00 pm
In the 13 TeV LHC data both experiments have observed an excess of events in searches for new particles that decay to pairs of photons. Although the data is still inconclusive, this could be the first direct sign of new physics beyond the Standard Model. In this talk, I will discuss the possibilities (and impossibilities) for new physics from…
Physics Group Meeting - IAS - Discussion group led by Ellis Ye Yuan, IAS, “Soft Gravitons”
Wed, Jan 20, 2016, 1:30 pm2:30 pm
We would like to discuss about soft gravitons. On the one hand, they enter in the soft theorems of gravity scattering which exhibit universal structures useful in the S-matrix program (e.g.,, On the other hand, they appear in the recent efforts of understanding the symmetries of…
Physics Group Meeting - IAS - Discussion group led by Carlos Mafra, IAS, “Perturbative String Scattering Amplitudes with the Pure Spinor Formalism
Wed, Jan 13, 2016, 1:30 pm2:30 pm
The pure spinor formalism is an alternative description of the superstring which is manifestly spacetime supersymmetric and can be covariantly quantized. As a consequence, in recent years many superstring amplitudes which were impractical to calculate using the standard formulations have been computed and the results show a surprising elegance. …
Physics Group Meeting - IAS - Discussion group led by John J. Carrasco, Member, IAS -“Color-Kinematics in Scattering Amplitudes”
Wed, Dec 16, 2015, 1:30 pm2:30 pm
Scattering amplitudes, in a wide variety of gauge theories, and independent of dimension and gauge group, have surprising kinematic structure which is currently only understood in terms of graphical rules relating the kinematic weights of graphs, in much the same way that the color-factors of graphs are related: namely by Jacobi and antisymmetry…
Special High Energy Theory Seminar - Zohar Komargodski, Weizmann Institute of Science - "Disordered Conformal Field Theories"
Tue, Dec 15, 2015, 12:30 pm1:30 pm
We consider Conformal Field Theories perturbed by quenched disorder. Such systems often flow to new, disordered, fixed points of the renormalization group. For the Ising model in d = 3 with random bonds, we calculate some properties of the disordered fixed point in perturbation theory in the heat capacity exponent. We compare with experimental…
High Energy Theory IAS - Daniel Roberts, Massachusetts Institute of Technology, “Chaos in Quantum Channels”
Mon, Dec 14, 2015, 2:30 pm3:30 pm
Motivated by black hole physics and holography, we study chaos, scrambling, and complexity by considering the entanglement properties of unitary operators. First, we develop a diagnostic of chaos by directly considering the time evolution of a simple local operator. This leads us to out-of-time-order (OTO) four-point functions as an indicator of…
High Energy Theory - Bruno Le Floch, Princeton University - "AGT correspondence for surface operators"
Fri, Dec 11, 2015, 1:45 pm3:00 pm
Compactifying 6d N=(2,0) superconformal theories on Riemann surfaces yields 4d N=2 gauge theories. The sphere partition function of such a 4d theory is equal to a CFT correlator on the Riemann surface. The correspondence can be enriched by including half-BPS operators of codimension 2 or 4 in the 6d N=(2,0) theory. Depending on their …
CM Seminar-B. Frandsen Columbia U-“From Mott insulators to Weyl fermions: Using muons, neutrons, & photons to probe unconventional states of matter"
Thu, Dec 10, 2015, 1:00 pm2:30 pm
to uncover the fundamental properties of these new topological phases of matter. The two most fruitful routes to novel states of matter in modern condensed matter physics have been through “strongly correlated electron materials,” where the strength of the interactions between electrons compares to or exceeds the other energy scales in the system…
Physics Group Meeting- IAS-Discussion group led by Hirosi Ooguri, Visiting Professor IAS - “Charactering CFT’s with Gravitational Description"
Wed, Dec 9, 2015, 1:30 pm2:30 pm
In the Friday seminar last week, Jennifer Lin talked about our joint work to characterize gravitational effective theories whose UV completions are dual to CFT’s on the boundary. I will discuss our attempt at its converse: how to characterize CFT’s that can be described by weakly coupled gravitational theories with smooth geometries [1]. I will…