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Discrete Approaches - 2
- Aaron Trout Chatham University
- Philipp Hoehn Okinawa Institute of Science and Technology Graduate University
July 25, 2013

PIRSA:13070075
Causal Dynamical Triangulations without Preferred Foliation

Renate Loll Radboud Universiteit Nijmegen

July 25, 2013

PIRSA:13070071
Towards a Consistent Quantum Dynamics for Euclidean LQG: A Weak Coupling Limit

Madhavan Varadarajan Raman Research Institute

July 25, 2013

PIRSA:13070080
Casual Sets and the Quantum Action

Fay Dowker Imperial College London

July 25, 2013

PIRSA:13070069
Asymptotic Dynamics: Spin Foam Partition Functions in an Asymptotic Regime

Frank Hellmann Max Planck Institute for Gravitational Physics - Albert Einstein Institute (AEI)

July 25, 2013

PIRSA:13070068
Spinfoam Formulation of Loop Quantum Gravity

Muxin Han Florida Atlantic University

July 24, 2013

PIRSA:13070067
Recently Obtained Non-Perturbative 1/N Expansion of Tensor Models

Razvan Gurau Universität Heidelberg

July 24, 2013

PIRSA:13070066
The Tensor Track

Vincent Rivasseau University of Paris-Saclay

July 24, 2013

PIRSA:13070065
Twistor Strings for N=8 Supergravity

David Skinner University of Cambridge

July 24, 2013

PIRSA:13070064
Spinor and Twistor Networks in Loop Gravity

Etera Livine French National Centre for Scientific Research (CNRS)

July 24, 2013

PIRSA:13070063
Renormalization - 2
- Joshua Cooperman Radboud Universiteit Nijmegen
- Mercedes Martin-Benito Complutense University of Madrid
- Sylvain Carrozza University of Burgundy
July 23, 2013

PIRSA:13070055
Quantum Cosmology - 3
- Guillermo Marugan Spanish National Research Council (CSIC)
- Manuel Kramer Universität zu Köln
- Matthew Johnson York University
- Sanjeev Seahra University of New Brunswick
July 23, 2013

PIRSA:13070058

Discrete Approaches - 2
- Aaron Trout Chatham University
- Philipp Hoehn Okinawa Institute of Science and Technology Graduate University
July 25, 2013

PIRSA:13070075
Causal Dynamical Triangulations without Preferred Foliation

Renate Loll Radboud Universiteit Nijmegen

July 25, 2013

PIRSA:13070071

We introduce a generalized version of the Causal Dynamical Triangulations (CDT) formulation of quantum gravity, in which the regularized, triangulated path integral histories maintain their causal properties, but do not have a preferred proper-time foliation. An extensive numerical study of the associated nonperturbative path integral in 2+1 dimensions shows that it can nevertheless reproduce the emergence of an extended de Sitter universe on large scales, a key feature of CDT quantum gravity. This suggests that the preferred foliation normally used in CDT is not a crucial (although convenient) part of its background structure.
Towards a Consistent Quantum Dynamics for Euclidean LQG: A Weak Coupling Limit

Madhavan Varadarajan Raman Research Institute

July 25, 2013

PIRSA:13070080

Spacetime covariance in canonical quantum gravity is tied to the existence of an anomaly free representation of its constraint algebra. I will argue that establishing the existence of such a representation in the LQG context requires the consideration of higher than unit density weight Hamiltonian constraints. Smolin's weak coupling limit of Euclidean gravity, while simpler than full blown gravity , still exhibits an open constraint algebra isomorphic to that of gravity and offers an ideal testing ground for the investigation of the quantum constraint algebra of such higher density constraints. I will report on recent progress on this issue in the context of an LQG type quantization of this system. Certain features of the constructions such as the encoding of the action of the quantum constraint in terms of operator valued diffeomorphisms may play a key role in the definition of a consistent quantum dynamics for LQG.
Casual Sets and the Quantum Action

Fay Dowker Imperial College London

July 25, 2013

PIRSA:13070069

The struggle between local and global concepts in physics comes to a head in causal set quantum gravity. Local physics -- and general relativity in particular -- must be recovered in a continuum approximation if the theory is to be successful but causal sets are inherently non-local entities. I will describe a family of causal set actions labelled by dimension, each of which is nonlocal and yet, when applied to certain causal sets, approximates the Einstein Hilbert action and is therefore effectively local. I will explain why this is a source of hope that causal set theory has a continuum approximation.
Asymptotic Dynamics: Spin Foam Partition Functions in an Asymptotic Regime

Frank Hellmann Max Planck Institute for Gravitational Physics - Albert Einstein Institute (AEI)

July 25, 2013

PIRSA:13070068

Spin foam models are models for space time built from discrete chunks of quantized geometry. In the asymptotic regime the classical geometry is regained.
In the last year we have seen rapid developments in our understanding of this geometry at the level of the entire partition function. In particular it was found that the geometries that contribute to the partition function in the asymptotic regime satisfy accidental curvature constraints.
I will discuss the classic results and role of asymptotics, the recent results and their impact on the interpretation of these models.
Spinfoam Formulation of Loop Quantum Gravity

Muxin Han Florida Atlantic University

July 24, 2013

PIRSA:13070067

Recently there are a lot of progresses in developing the spinfoam formulation of loop quantum gravity. In this talk I give an overview of the subject. I introduce the formalism and the motivation of the theory, and I discuss the application of spinfoam formulation in black hole and cosmology. I also discuss the inclusion of the quantum matter fields and cosmological constant in the formalism. The inclusion of cosmological constant motivates a Chern-Simons formulation of LQG. Finally I discuss the semiclassical low-energy approximation of the spinfoam formulation, where Einstein gravity appears as the leading contribution.
Recently Obtained Non-Perturbative 1/N Expansion of Tensor Models

Razvan Gurau Universität Heidelberg

July 24, 2013

PIRSA:13070066

I will present the recently obtained non perturbative 1/N expansion of tensor models. The correlation functions are shown to be analytic in the coupling constant in some domain of the complex plane and to support appropriate scaling bounds at large N. Surprisingly, the non perturbative setting turns out to be a powerful computational tool allowing the explicit evaluation order by order (with bounded rest terms) of the correlations.
The Tensor Track

Vincent Rivasseau University of Paris-Saclay

July 24, 2013

PIRSA:13070065

I will present the tensorial renormalization group approach to quantum gravity and the tentative scenario it suggests for the emergence of space-time.
Twistor Strings for N=8 Supergravity

David Skinner University of Cambridge

July 24, 2013

PIRSA:13070064

The perturbative S-matrix of General Relativity has a rich and fascinating geometric structure that is completely obscured by its traditional description in terms of Feynman diagrams. I'll explain a new way of looking at four dimensional supergravity: as a string theory in twistor space. All tree-level amplitudes in the theory can be described by algebraic curves in Penrose's nonlinear graviton
Spinor and Twistor Networks in Loop Gravity

Etera Livine French National Centre for Scientific Research (CNRS)

July 24, 2013

PIRSA:13070063

I will review the reformulation of the loop gravity phase space in terms of spinor networks and twistor networks, and present how these techniques can be used to write spinfoam amplitudes as discretized path integrals and to study the dynamics that they define (recursion, Hamiltonian constraints as differential equations).
Renormalization - 2
- Joshua Cooperman Radboud Universiteit Nijmegen
- Mercedes Martin-Benito Complutense University of Madrid
- Sylvain Carrozza University of Burgundy
July 23, 2013

PIRSA:13070055
Quantum Cosmology - 3
- Guillermo Marugan Spanish National Research Council (CSIC)
- Manuel Kramer Universität zu Köln
- Matthew Johnson York University
- Sanjeev Seahra University of New Brunswick
July 23, 2013

PIRSA:13070058

Title	Date	Collection	Type	Info
Discrete Approaches - 2	2013‑07‑25	Loops 13	Conference	View details
Causal Dynamical Triangulations without Preferred Foliation	2013‑07‑25	Loops 13	Conference	View details
Towards a Consistent Quantum Dynamics for Euclidean LQG: A Weak Coupling Limit	2013‑07‑25	Loops 13	Conference	View details
Casual Sets and the Quantum Action	2013‑07‑25	Loops 13	Conference	View details
Asymptotic Dynamics: Spin Foam Partition Functions in an Asymptotic Regime	2013‑07‑25	Loops 13	Conference	View details
Spinfoam Formulation of Loop Quantum Gravity	2013‑07‑24	Loops 13	Conference	View details
Recently Obtained Non-Perturbative 1/N Expansion of Tensor Models	2013‑07‑24	Loops 13	Conference	View details
The Tensor Track	2013‑07‑24	Loops 13	Conference	View details
Twistor Strings for N=8 Supergravity	2013‑07‑24	Loops 13	Conference	View details
Spinor and Twistor Networks in Loop Gravity	2013‑07‑24	Loops 13	Conference	View details
Renormalization - 2	2013‑07‑23	Loops 13	Conference	View details
Quantum Cosmology - 3	2013‑07‑23	Loops 13	Conference	View details

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