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Quantum Fields and Strings

This series consists of talks in the area of Quantum Fields and Strings.

Seminar Series Events/Videos

Currently there are no upcoming talks in this series.
 

 

Mardi jan 12, 2021
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In this talk I will discuss the universal properties of thermal transport in conformal field theories that are perturbed by a TTbar operator. TTbar-deformation is known to be an exactly solvable deformation in that the spectrum of the undeformed theory alone suffices to predict that of the deformed theory. Unique properties of TTbar deformation allow us to study the TTbar-deformed CFTs using two disparate methods: integrability and holography. I will apply these two approaches to study the non-equilibrium steady states and Drude weights, finding perfect agreement.

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Mardi déc 15, 2020
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The Ryu Takayanagi formula identifies the area of  extremal surfaces in AdS with the entanglement entropy of the boundary CFT. However the bulk microstate interpretation of the extremal area remains mysterious. Progress along this direction requires understanding how to define entanglement entropy in the bulk closed string theory. As a toy model for AdS/CFT, we study the entanglement entropy of closed strings in the topological A model in the context of Gopakumar Vafa duality.

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Mardi déc 08, 2020
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Dilaton-gravity models are integrable in two dimensions and admit a holographic description. In this talk, the holographic description of the Dilaton-gravity in flat spacetime is discussed. Using the gauge theory formulation of the model we obtain the boundary action which under certain boundary conditions is of the Warped-Schwarzian type. We calculate the 1-loop partition function of the model as the coadjoint orbit of the warped Virasoro group.

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Mardi déc 01, 2020
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I will review the numerical approach to testing gauge/gravity duality using matrix models. This will lead to a summary of recent results from the BFSS, BMN and Berkooz-Douglas matrix models and a strong non-perturbative test of gauge/gravity duality.

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Mercredi nov 25, 2020
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There is a deep relation between classical error-correcting codes, Euclidean lattices, and chiral 2d CFTs. We show this relation
extends to include quantum codes, Lorentzian lattices, and non-chiral CFTs. The relation to quantum codes provides a simple way to solve

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Mardi nov 24, 2020
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I will study quantum error correcting codes that model aspects of the AdS/CFT correspondence. In an algebraic approach I will demonstrate the existence of a consistent assignment, to each boundary region, of conditional expectations that preserve the code subspace. This allows us to give simple derivations of well known results for these holographic code, and also to derive a few new results. 

I will also make a connection to the theory of QFT super-selection sectors.

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Mardi nov 10, 2020
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I will present a holographic framework for reconstructing the experience of bulk observers in AdS/CFT. In particular, I will show how to recover the proper time and energy distribution measured along bulk worldlines, directly in the CFT via a universal, background-independent prescription. For an observer falling into an eternal AdS black hole, the proposal resolves a conceptual puzzle raised by Marolf and Wall.

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Mardi oct 27, 2020
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Universal relationships between asymptotic symmetries, QFT soft theorems, and low energy observables have reinvigorated attempts at flat space holography. In this talk, I will review recent advances in the celestial holography proposal, where the 4d S-matrix is reconsidered as a 2d correlator on the celestial sphere at null infinity.

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Mardi oct 20, 2020
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There are several important conceptual and computational questions concerning path integrals in QM and QFT, which have recently been approached from new perspectives motivated by "resurgent asymptotics", a novel mathematical formalism that seeks to unify perturbative and non-perturbative physics. I will discuss the basic ideas behind the connections between resurgent asymptotics and physics, ranging from differential equations to phase transitions and QFT.

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Mardi oct 13, 2020

 I will discuss how central extensions of charge algebras in gravitational theories with null boundaries arise from an anomalous transformation of the boundary term in the gravitational action. This parallels the way in which the holographic Weyl anomaly appears in AdS/CFT, with the ambiguity in the normalization of the null generator being the analogue of the choice of Weyl frame.

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