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Thomas Hertog (KU Leuven)17/04/2023, 10:00
I explain how quantum corrections to the entropy of four-dimensional de Sitter space can be computed using the AdS/CFT correspondence. Employing the intertwinement of Euclidean de Sitter and anti de Sitter saddles, I embed effective de Sitter gravity theories in M-theory and conjecture that the partition function of the ABJM CFT dual encodes all perturbative corrections to the de Sitter...
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Dionysios Anninos (King's College London)17/04/2023, 11:30
It has been argued by several authors that the underlying state space might be finite dimensional in quantum de Sitter. We discuss this idea, and how recent developments, from a variety of perspectives, might help to refine and substantiate it.
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Eva Silverstein (Stanford)17/04/2023, 14:30
We start by highlighting the convergence of several concrete research threads (among many) illuminating basic statistical mechanical properties of dS. In this line of development, the solvable TT-bar(+Λ2) deformation recently provided an explicit microstate count for the dS3 cosmic horizon, reproducing the refined Gibbons-Hawking entropy computed in https://arxiv.org/abs/2009.12464 along with...
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Thomas van Riet (KU Leuven)17/04/2023, 16:00
I will first discuss briefly the status of dS space in string theory and related Swampland insights. I will attempt to draw connections between discussions on dS space in quantum cosmology to the Swampland and string theory. In doing so I will describe a proposal for a top-down de Sitter construction, and how it differs from the Hartle-Hawking state. I will end with a discussion about...
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Gonçalo Araújo Regado (University of Cambridge)17/04/2023, 17:00
In this talk I will introduce the formalism of Cauchy Slice Holography, which provides a holographic description of Wheeler-DeWitt states in the canonical formulation of quantum gravity in terms of partition functions of T^2-deformed CFTs. The field theory lives on a spatial slice of the bulk. I will then explore some of the consequences of such a description of quantum gravity for a closed...
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Damián Galante (King's College London)18/04/2023, 10:00
In two dimensions, the static patch of de Sitter can be accessed by observers sitting at the boundary of an AdS spacetime. This idea suggests that certain RG flows in the dual quantum mechanical theory should capture effects of quantum de Sitter space.
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In this talk, I will explore tractable RG flows in the SYK model and discuss their implications to describe static patch physics at a... -
Tarek Anous (Queen Mary University of London)18/04/2023, 11:30
Unitarity in de Sitter is mired with potential pitfalls. One of them is that massive particles are represented by (so-called principal series) states with complex conformal dimensions. Even more confusing is that states with positive conformal dimensions and a bounded spectrum, known as the discrete series, are, at the free-field level, represented as scalar tachyons with a finely tuned mass,...
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César Gómez (ift uam-csic madrid)18/04/2023, 14:30
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Beatrix Mühlmann (McGill)18/04/2023, 16:00
In this talk I will discuss the interplay between supersymmetry and two-dimensional de Sitter space. In particular we consider a gauge fixed form of 2d supergravity coupled to an N=2 superconformal field theory. The resulting theory is known as N= 2 Liouville theory and also makes an appearance as the non-critical superstring theory. N=2 super Liouville admits a positive cosmological constant...
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Leonard Susskind (Stanford)18/04/2023, 16:30
Semiclassical gravity and the holographic description of the static patch of de Sitter space appear to disagree about properties of correlation functions. Certain holographic correlation functions are necessarily real whereas their semiclassical counterparts have both real and imaginary parts. The resolution of this apparent contradiction involves the fact that time-reversal is a gauge...
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Alejandra Castro (University of Cambridge)19/04/2023, 10:00
In this talk I will discuss a novel mechanism that couples matter fields to three-dimensional de Sitter quantum gravity. This construction is based on the Chern-Simons formulation of three-dimensional Euclidean gravity, and it centers on a collection of Wilson loops winding around Euclidean de Sitter space. We coin this object a Wilson spool. To construct the spool, we build novel...
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Jan Pieter van der Schaar (University of Amsterdam)19/04/2023, 11:30
I will discuss some progress in our understanding of the Euclidean action of de Sitter (charged) black hole spacetimes and their contributions in a Euclidean path integral approach, using a constrained instanton formalism. In a first attempt to start understanding non-perturbative corrections to de Sitter correlators, I will then describe how the the late-time behavior of de Sitter correlators...
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Konstantinos Skenderis (University of Southampton)19/04/2023, 14:30
In-in correlation functions in de Sitter may be related to AdS amplitudes and three-dimensional CFT correlators in multiple ways, each having different features but with only one of them being consistent with the dual theory being a local CFT. In this talk I will discuss the different possibilities and present holographic formulas for 2-, 3- and 4-point functions.
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Marija Tomašević (CPHT, Ecole Polytechnique)19/04/2023, 16:00
In three-dimensional de Sitter space classical black holes do not exist, and the Schwarzschild-de Sitter solution instead describes a conical defect with a single cosmological horizon. We argue that the quantum backreaction of conformal fields can generate a black hole horizon, leading to a three-dimensional quantum de Sitter black hole. Its size can be as large as the cosmological horizon in...
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19/04/2023, 17:00
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Guilherme Pimentel (Scuola Normale Superiore)20/04/2023, 10:00
I will describe a geometric picture for cosmological perturbation theory. Through this geometry, we can determine differential equations satisfied by these correlators, as functions of their momenta. In this ``holographic” picture, cosmological time evolution is encoded in a sort of Hamiltonian (a flat connection) in kinematic space. I will also show how to move away from the highly symmetric...
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Gizem Sengor (Bogazici University)20/04/2023, 11:30
In quantum field theory on flat spacetime, analysis of the representations of the isometry group of spacetime with a vanishing cosmological constant has led to our current understanding of particle physics. In this talk we would like to discuss what can be learned about particles of a spacetime in the presence of a positive cosmological constant by studying the representations of the isometry...
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Suvrat Raju (Tata Institute for Fundamental Research)20/04/2023, 14:30
We obtain all solutions of the Wheeler-DeWitt equation with positive
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cosmological constant for a closed universe in the large-volume limit.
We define a natural norm on the solution space and thereby obtain a
description of the Hilbert space of quantum gravity in an asymptotically
de Sitter spacetime. This provides the finite G_N generalization of the
Hilbert space constructed by... -
Kamran Salehi Vaziri (University of Amsterdam)20/04/2023, 16:00
There has been an extensive series of works aimed at understanding the non-perturbative QFT in AdS and Minkowski spacetime using bootstrap techniques. Implementing these techniques to QFT in dS requires a concrete understanding of Hilbert space decomposition into Unitary Irreducible Representation (UIR) of the dS symmetry group. In this spirit, we study the decomposition of the tensor product...
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Edgar Shaghoulian (University of California Santa Cruz)21/04/2023, 10:00
The central dogma of black hole physics – which says that from the outside a black hole can be described in terms of a quantum system with exp(Area/4G) states evolving unitarily – has recently been supported by computations indicating that the interior of the black hole is encoded in the Hawking radiation of the exterior. In this talk, we probe whether such a dogma for cosmological horizons...
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Andrew Strominger (Harvard University)21/04/2023, 11:30
We show in the context of dS/CFT that de Sitter spacetime emerges from quantum entanglement between two copies of the holographically dual CFT.
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Lars Aalsma (Arizona State University)21/04/2023, 14:30
In recent years, our understanding of (entanglement) entropy in gravitational systems has led to remarkable insights into the nature of black holes and in particular the discovery of entanglement islands. In this talk, I will discuss to what extent these developments can be applied to the de Sitter horizon in JT gravity. I will stress the important differences of black hole vs. cosmological...
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Erik Verlinde (University of Amsterdam)21/04/2023, 16:00
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Yusuke Taki (Yukawa Institute for Theoretical Physics)21/04/2023, 17:00
In this talk, we consider the holographic relation for quantum entanglement in dS/CFT as an extension of Ryu-Takayanagi formula in AdS/CFT. We argue that the holographic formula holds for pseudo entropy, which is a complex-valued generalization of entanglement entropy. Also time-like entanglement entropy is introduced in AdS/CFT as a counterpart of pseudo entropy in dS/CFT. We elaborate...
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