Viewing fundamental physics processes through the lenses of quantum information storage and processing is a new frontier in gravity and quantum field theory. Much of what we have learnt in the past decade builds on the notion of entanglement and its entropy. The latter quantifies how hard it is to store a quantum-many body state of interest on a classical computer. Complexity is a new player in the high-energy physics context and quantifies how hard it is to prepare a quantum-many body state using limited resources. Learning from the success story of entanglement entropy, establishing universal results on complexity in two-dimensional conformal field theories should open many new research directions, including finding a precise gravity dual. I will discuss recent progress on this problem reported in 2005.02415 and 2007.11555 with Flory.

Recording: https://uky.zoom.us/rec/share/UsIbWHaXi4DJ04EDDouJbMB0CPmJUvY0bCQSf5jIhZNJBPJE5-TTbj-Oq4NWVtYr.xSXcjGefvoy1F8o2

Abstract:

A universal relationship between asymptotic symmetries, QFT soft theorems, and low energy observables has reinvigorated attempts at flat space holography.  In this talk we introduce a map from 4d S-matrix elements to 2d correlators in the putative dual Celestial CFT.  In particular, we will focus on recent progress towards understanding elements of the IR triangle from the perspective of our Celestial CFT.

Note the unusual start time!

Recording: https://uky.zoom.us/rec/play/-Jlt4l4Zj7OW4tELdw9Yj4zi5p4rvUrm3OLcosykvV…

We explore the possibility of embedding a dS_2 universe in the interior of an asymptotically AdS_2 spacetime. We consider the problem macroscopically, discussing various constraints from gravitational models. We also discuss potential microscopic paths guided by the perspective of AdS_2 holography. 

Zoom Link : https://uky.zoom.us/j/95988631148

Abstract : We analyse Virasoro blocks as an expansion in heavy exchange dimension. For the one point torus block and the four point sphere block each order in the expansion can be written as polynomials in the Eisenstein series. These polynomials are further constrained to satisfy a recursion relation, which can be re-expressed as a noiseless KPZ equation for the blocks. This structure can be utilized along with the Zamolodchikov recursions to develop an algorithm to construct blocks in the heavy regime. We apply our results to find the corrections to averaged heavy-heavy-light OPE coefficients.

https://uky.zoom.us/j/99297500671

Recording: https://uky.zoom.us/rec/share/AsE8BaVwSqD1qJKmwnYn39GqIfhuLzqQjpTYGxwQB9C00GKOFaZtuuRURVNvSzTn.YsBz5vtRuhDXhbwZ

 In this talk, we review an approach to describing cosmological

physics using ordinary AdS/CFT, where the cosmological physics is the

effective description of an end-of-the-world brane which cuts off the

second asymptotic region of a two-sided black hole. The worldvolume

geometry of the brane is an FRW big-bang/big-crunch spacetime. In

favorable circumstances, the brane acts as a Randall-Sundrum Planck

brane so that gravity localizes. We describe a microscopic construction

for such an end-of-the-world brane with localized gravity in AdS/CFT,

starting from N=4 SYM theory. We suggest specific microscopic states of

N=4 SYM theory that may encode the physics in a four-dimensional

cosmological spacetime.

A large number of Majorana fermions with interactions coupling four of them at a time can exhibit interesting quantum dynamics. Models of this kind include the Sachdev-Ye-Kitaev (SYK) model, where the coefficients of quartic interactions are randomly distributed, and the Tensor models, where they respect continuous symmetries. These models exhibit approximate invariance under scaling of the time and have power law fall-off of the correlation functions.

In this talk we will discuss a pair of SYK or Tensor models coupled by the quartic interactions, and show that they produce a richer set of phenomena. These include a line of fixed points, where critical exponents vary along the line and formally acquire imaginary parts outside it. For one sign of the coupling constant, the approximate scale invariance continues to hold. For the other, a gap opens in the energy spectrum, resulting in exponential fall-off of correlation functions. This is indicative of breaking of a discrete symmetry. Thus, our quantum mechanical model exhibits dynamical phenomena characteristic of higher dimensional quantum field theories. Furthermore, the gapped phase of our model may be dual to a certain traversable wormhole in two-dimensional space-time.

The talk will end with a similar discussion of a pair of complex SYK models coupled by a quartic interaction which preserves the U(1) x U(1) symmetry. For a range of parameters, this model gives rise to breaking of one of the U(1) symmetries. This is demonstrated via an analysis of the large N Dyson-Schwinger equations, as well as by Exact Diagonalizations of the finite N Hamiltonians.

Zoom link : https://uky.zoom.us/j/97553578130

Recording: https://uky.zoom.us/rec/play/rTWoRCvq8JEfgyyhHKGAlcV2a6XRi8DwaILPRPBY_Y…-?continueMode=true

In the past decade, renewed interest in the nucleon electromagnetic form factors was sparked by new measurements of electron-proton scattering at low Q^2 by the A1 Collaboration and of the proton charge radius in muonic hydrogen by the CREMA Collaboration. Subsequent theoretical developments re-examined longstanding assumptions on the parameterizations of these form factors. In this talk, I will review some of these developments, then present new parameterizations of the form factors that are the result of work in the past few years. Finally, I will outline applications of these form factors in both atomic physics and for the US program of precision neutrino measurements.

Recorded talk and slides: https://www.dropbox.com/sh/sek9spcry22xorw/AABHxLmJwsrae-E0zEftz7HWa?dl=0