Events Archive

IAS HET Seminar | Matthew Hastings, Microsoft| “The Sum-of-Squares for Fermionic Systems, and the SYK Model” | Zoom Only
Mon, May 15, 2023, 2:30 pm2:30 pm

Perhaps the most important problem in physics or quantum chemistry is to determine properties of the ground state of an interacting system of fermions.  As a quantum mechanical problem, there may be no efficient classical witness to the ground state energy, or even to an approximation of that energy.  A…

HET Seminar |Lorenz Eberhardt, Member, School of Natural Sciences, IAS| “Evaluating one-loop string amplitudes” | PCTS & Zoom
Fri, May 12, 2023, 1:45 pm1:45 pm

 I will explain recent work with S. Mizera in which we give explicit evaluations of one-loop open string amplitudes at finite alpha’. Our method involves various deformations of the contour integral over the modular parameter. We directly verify that the one-loop string amplitude satisfies unitarity constraints. I…

The Standard Model heavyweights: an overview of the latest measurements of the ttW and four-tops processes by the ATLAS experiment|Brendon Bullard
Thu, May 11, 2023, 2:00 pm3:00 pm

Abstract: Measurements of rare Standard Model (SM) processes are now possible thanks to the large trove of collision data delivered by the LHC during its second data taking run. Of particular interest are heavy states including top quarks plus an additional heavy boson (ttH, ttW, and ttZ) and the simultaneous production of four top quarks…

Faculty, post docs, grads
Dark Cosmos - Putting all the X in one basket: X-ray constraints on sub-GeV dark matter |Elena Pinetti, Fermilab| Joseph Henry Rm 5/9 @4PM
Tue, May 9, 2023, 4:00 pm5:00 pm

In this talk I will focus on light dark matter particles, with a mass between 1 MeV and a few GeV. These particles can annihilate or decay into electron-positron pairs which can upscatter the low-energy fields in our Galaxy and produce X-ray emission. By using the X-ray data from XMM-Newton, Integral, Suzaku and NuStar, we derive strong…

Physic faculty, post docs, grads
Condensed Matter: Fluid dynamics of Incompressible Quantum Hall fluids| F. Duncan M. Haldane|Prof of Physics, Princeton University|JH Rm 5/9 @12PM
Tue, May 9, 2023, 12:00 pm1:00 pm

While Laughlin identified the fractional quantum Hall state as a consequence of an “incompressible quantum fluid”, well-described by his model  wavefunction  which exhibits “flux attachment”, no fundamental explanation of the energetics driving “flux attachment” has emerged. A new picture reveals that  a…

Physics faculty, post docs, grads
IAS HET Seminar | Savas Dimopoulos, SITP, Stanford University| “The Cosmic Neutrino Background (CνB): Its Distribution on the Surface of the Earth and its Manipulation by Laboratory-Scale Diffraction Gratings” | Bloomberg Lecture Hall & Zoom
Mon, May 8, 2023, 2:30 pm2:30 pm

The CνB is a cosmological relic analogous to the CMB, and contains information about the universe before it was one-second-old. Reflection of relic neutrinos from the surface of the Earth creates a significant local neutrino-antineutrino asymmetry in a shell seven meters thick around the Earth's surface. This asymmetry…

Biophysics Seminar Series - Lillian Fritz-Laylin
Mon, May 8, 2023, 12:30 pm1:30 pm

Eukaryotic cells physically manipulate their environments; swimming through liquids, crawling across surfaces, and actively ingesting objects large and small. Inside these cells lies a seething mass of cytoplasm through which thousands of different objects are pushed and pulled to specific cellular locations. These and other dynamic processes…

IAS HET Seminar | Matthew Heydeman, Member, School of Natural Sciences, IAS| “Supersymmetric Black Holes, Defects, and Phase Transitions” | Bloomberg Lecture Hall & Zoom
Fri, May 5, 2023, 1:45 pm3:00 pm

Supersymmetric black holes in Anti de-Sitter space have recently been shown to have a large number of exactly degenerate microstates. In the first part of the talk, we will review how AdS5 black hole microstates may be reliably counted in the dual N=4 SYM theory using the superconformal index, a partition function preserving 1/16-supersymmetry…

Special Seminar:Josephson junction arrays as a platform for topological phases of matter|Omri Lesser (Weizmann Inst)|May 4 @3:30pm Joseph Henry Rm
Thu, May 4, 2023, 3:30 pm5:00 pm

The search for low-dimensional topological superconductivity is fueled by the promise of new and exotic physics, such as chiral superconductivity and non-Abelian anyons. However, the need to break time-reversal symmetry, usually by applying a relatively large external magnetic field, has hindered the realization of these novel phases of matter…

Physics faculty, post docs, grads
Condensed Matter:Instanton Density Operator in Lattice QCD from Higher Category Theory | Jingyuan Chen ,Tsinghua University (Beijing)|A06 5/1 @2PM
Mon, May 1, 2023, 2:30 pm3:30 pm

A long standing problem in lattice QCD is to construct an explicit instanton density operator on the lattice. We introduce such a construction, after suitably refining the lattice Yang-Mills action, so that it captures the continuum Yang-Mills theory better than the traditional lattice Yang-Mills action does. This refinement needed follows…

Physics faculty, post docs, grads
PGI Seminar Series Spring 2023|Stephen Adler|IAS|"Dynamical Gravastars"
Mon, May 1, 2023, 12:30 pm1:30 pm

I give new results for  “gravastars'', which are horizonless compact objects that closely mimic mathematical black holes in their exterior geometry,  but for which g_{00} is always positive.  They result from  solving the  Tolman-Oppenheimer-Volkoff  (TOV) equations for relativistic stellar structure, which require…

Biophysics Seminar Series - Arseny Finkelstein
Mon, May 1, 2023, 12:30 pm1:30 pm

Regulation of information flow in the brain is critical for many forms of behavior.

In the first part of my talk, I will focus on mechanisms that regulate interactions between brain regions and describe how state-dependent frontal cortex dynamics can gate information flow from the sensory cortex during decision-making in mice.

HET Seminar |Howard Georgi, Harvard| “Fun with n-flavor Schwinger models” | PCTS & Zoom
Fri, Apr 28, 2023, 1:45 pm1:45 pm

I will describe the correlators of fermion bilinears in the n-flavor massless Schwinger model. These are exactly calculable generalized free theories. For n > 1, there is a massive particle and a conformal sector. I have argued that in the n = 2 theory, very special mass terms can be added to introduce interactions…

HET Seminar |Yiyang Jia, Weizmann Institute of Science| “Parisi's hypercube, Fock-space frustration and NAdS$_2$/NCFT$_1$ holography” | PCTS & Zoom
Thu, Apr 27, 2023, 2:30 pm2:30 pm

We consider a model of Parisi where a single particle hops on an infinite-dimensional hypercube, under the influence of a uniform but disordered magnetic flux.  We reinterpret the hypercube as the Fock-space graph of a many-body Hamiltonian, and the flux as a frustration of the return amplitudes in Fock space. We…

Dark Cosmos - New precision cosmological constraints from CMB lensing with the Atacama Cosmology Telescope|Matthew Madhavacheril|Joseph Henry Rm@4PM
Tue, Apr 25, 2023, 4:00 pm5:00 pm

The Atacama Cosmology Telescope is a ground-based CMB survey that has mapped half the millimeter sky at significantly higher resolution and sensitivity than the Planck satellite. I will present new ACT results from a 9400 sq.deg. gravitational lensing mass map, including constraints on the amplitude of matter fluctuations as well as the Hubble…

Physics faculty, post docs, grads
Condensed Matter:Identification and Determination of the Topological Order of a Non-Abelian State (The 5/2 FQHE State)|Moty Heiblum|Braun Center for Sub-Micron Research, Department of Condensed Matter Physics
Tue, Apr 25, 2023, 12:00 pm1:30 pm

Studying non-abelian anyons is exciting due to their unique braiding statistics. The 5/2 quantum Hall state has been long proposed to host such localized quasiparticles in the 2D bulk. Resting on ‘bulk-edge’ correspondence, their gapless edge modes are expected to mirror the topological order of the 5/2 quantum state. Supporting an odd number…

Physics faculty, post docs, grads
Biophysics Seminar: José Alvarado, University of Texas Austin| Connecting active “hardware” to biological “software”
Mon, Apr 24, 2023, 12:30 pm1:30 pm

The actomyosin cytoskeleton is a naturally occurring active gel found in virtually all mammalian cells. Its ability to contract allows cells to move, change shape, exert force, sense stiffness, and maintain constant tension. In order for the “hardware” of actomyosin gels to support such a diverse set of mechanical tasks, it is tightly coupled…

This event is free and open to the public.
Special Seminar: (Machine) Learning of Dark Matter| Lina Necib (MIT)|Joseph Henry Rm @3PM
Fri, Apr 21, 2023, 3:00 pm4:30 pm

In this talk, I present different machine learning and data driven techniques that produce measurements of stellar kinematics around the Milky Way, and relate them to our understanding of Dark Matter. More specifically, I will discuss a data driven technique applied to Gaia DR3 combined with Apogee data to produce the circular velocity…

Physics faculty, post docs, grads
IAS HET Seminar | Dalimil Mazac, Member, School of Natural Sciences, IAS| “Conformal Measure Spaces” | Bloomberg Lecture Hall & Zoom
Fri, Apr 21, 2023, 1:45 pm3:00 pm

The conformal bootstrap equations in general dimension are an infinite set of coupled non-linear equations in infinitely many variables. According to the lore, the solutions of the full set of equations correspond to physical CFTs. At the same time, the only solutions truly known to exist above two dimensions are the mean field theories. In…