Renormalization in Background Independent Theories: Foundations and Techniques

COVID-19 information for PI Residents and Visitors

Conference Date:

Monday, September 28, 2015 (All day) to Friday, October 2, 2015 (All day)

Pirsa Collection:

Scientific Areas:

Quantum Gravity

Renormalization concepts have been recently shown to be essential for the formulation and understanding of background independent theories such as quantum gravity, as well as for extracting physical predictions from such theories. The workshop will discuss and review recent advances on this topic, both on the conceptual and technical side. It aims to intensify and start collaborations among the different groups working on renormalization, in particular in loop quantum gravity, spin foams and group field theory.

Benjamin Bahr, University of Hamburg
Vadim Belov, University of Hamburg
Valentin Bonzom, Université Paris 13
Sylvain Carrozza, CPT Marseille
Linqing Chen, Perimetr Institute
Clement Delcamp, Perimeter Institute
Bianca Dittrich, Perimeter Institute
Laurent Freidel, Perimeter Institute
Marc Geiller, Perimeter Institute
Lisa Glaser, University of Nottingham
Jeff Hnybida, Radboud Universiteit Nijmegen
Sebastian Kloeser, University of Hamburg
Etera Livine, École Normale Supérieure de Lyon
Sebastian Mizera, Perimeter Institute
James Quach, University of Tokyo
Aldo Riello, Perimeter Institute
Erik Schnetter, Perimeter Institute
Sebastian Steinhaus, University of Hamburg
Guifre Vidal, Perimeter Institute
Wolfgang Wieland, Perimeter Institute
Jose Zapata, Universidad Nacional Autonoma de Mexico (UNAM) Morelia

Benjamin Bahr, University of Hamburg
Andrzej Banburski, Perimeter Institute
Vadim Belov, University of Hamburg
Valentin Bonzom, Université Paris 13
Sylvain Carrozza, CPT Marseille
Linqing Chen, Perimeter Institute
Clement Delcamp, Perimeter Institute
Bianca Dittrich, Perimeter Institute
Maite Dupuis, University of Waterloo
Laurent Freidel, Perimeter Institute
Marc Geiller, Perimeter Institute
Florian Girelli, University of Waterloo
Lisa Glaser, University of Nottingham
Philipp Hoehn, Perimeter Institute
Jeff Hnybida, Radboud Universiteit Nijmegen
Sebastian Kloeser, University of Hamburg
Seth Kurankyi Asante, Perimeter Institute
Etera Livine, École Normale Supérieure de Lyon
Jonah Miller, Perimeter Institute
Sebastian Mizera, Perimeter Institute
Prince Osei, Perimeter Institute
Abdulmajid Osumanu, University of Waterloo
James Quach, University of Tokyo
Julian Rennert, ITP University of Heidelberg
Aldo Riello, Perimeter Institute
Erik Schnetter, Perimeter Institute
Giuseppe Sellaroli, University of Waterloo
Barak Shoshany, Perimeter Institute
Vasudev Shyam, Perimeter Institute
Lee Smolin, Perimeter Institute
Sebastian Steinhaus, University of Hamburg
Paul Tiede, University of Waterloo
Guifre Vidal, Perimeter Institute
Wolfgang Wieland, Perimeter Institute
Jose Zapata, Universidad Nacional Autonoma de Mexico (UNAM) Morelia

Monday, September 28, 2015

Time	Event	Location
8:30 – 9:00am	Registration	Reception
9:00 – 9:05am	Welcome and Opening Remarks	Space Room
9:05 – 10:30am	Wolfgang Wieland, Perimeter Institute TBA	Space Room
10:30 – 11:00am	Coffee Break	Bistro – 1^st Floor
11:00 – 12:30pm	Benjamin Bahr, University of Hamburg TBA	Space Room
12:30 – 2:00pm	Lunch	Reflecting Lounge
2:00 – 3:00pm	Valentin Bonzom, Université Paris 13 TBA	Space Room
3:00 – 3:30pm	Coffee Break	Bistro – 1^st Floor
3:30 – 5:30pm	Discussion: Bianca Dittrich, Perimeter Institute Lorentzian vs Euclidean approaches to quantum gravity	Space Room

Tuesday, September 29, 2015

Time	Event	Location
9:00 – 10:30am	Guifre Vidal, Perimeter Institute Tensor Network Renormalization	Space Room
10:30 – 11:00am	Coffee Break	Bistro – 1st Floor
11:00 – 12:30pm	Bianca Dittrich, Perimeter Institute TBA	Space Room
12:30 – 2:00pm	Lunch	Reflecting Lounge
2:00 – 3:00pm	Jose Zapata, Universidad Nacional Autonoma de Mexico Observable currents for effective field theories and their context	Space Room
3:00 – 3:30pm	Coffee Break	Bistro – 1st Floor
3:30 – 5:30pm	Discussion: Benjamin Bahr, University of Hamburg What is a theory of quantum gravity?	Space Room

Wednesday, September 30, 2015

Time	Event	Location
9:00 – 10:30am	Erik Schnetter, Perimeter Institute Efficient numerical methods for modern computing systems	Space Room
10:30 – 11:00am	Coffee Break	Bistro – 1st Floor
11:00 – 12:00pm	Lisa Glaser, University of Nottingham A chain of geometries	Space Room
12:00 – 1:00pm	Sebastian Steinhaus, University of Hamburg TBA	Space Room
1:00 – 2:30pm	Lunch	Reflecting Lounge
2:30 – 3:30pm	Clement Delcamp, Perimeter Institute TBA	Space Room
3:30 – 4:00pm	Coffee Break	Bistro – 1st Floor
4:00 – 6:00pm	Discussion: Vadim Belov, University of Hamburg Sebastian Kloeser, University of Hamburg Sebastian Mizera, Perimeter Institute Computational approach to coarse graining	Space Room
6:00pm	Banquet	Reflecting Lounge

Thursday, October 1, 2015

Time	Event	Location
9:00 – 10:30am	Jeff Hnybida, Radboud Universiteit Nijmegen TBA	Space Room
10:30 - 10:35am	Conference Photo	TBA
10:35 – 11:00am	Coffee Break	Bistro – 1st Floor
11:00 – 12:30pm	Etera Livine, École Normale Supérieure de Lyon TBA	Space Room
12:30 – 2:00pm	Lunch	Reflecting Lounge
2:00 – 3:00pm	James Quach, University of Tokyo Gravitational Casimir Effect	Space Room
3:00 – 3:30pm	Coffee Break	Bistro – 1st Floor
3:30 – 5:30pm	Discussion: Valentin Bonzom, Université Paris 13 Aldo Riello, Perimeter Institute Analytical Methods for Coarse Graining	Space Room

Friday, October 2, 2015

Time	Event	Location
9:00 – 10:30am	Sylvain Carrozza, Radboud Universiteit Nijmegen TBA	Space Room
10:30 – 11:00am	Coffee Break	Bistro – 1st Floor
11:00 – 12:00pm	Marc Geiller, Perimeter Institute TBA	Space Room
12:10 - 12:30pm	Linqing Chen, Perimeter Institute TBA	Space Room
12:30 – 2:00pm	Lunch	Reflecting Lounge
2:00 – 3:00pm	Discussion: Laurent Freidel, Perimeter Institute Summing vs Refining	Space Room

Lisa Glaser, University of Nottingham

A chain of geometries

The path integral is a very elegant formulation of quantum theory. It can also be an incredibly useful one, since it allows us to use methods of statistical physics, like computer simulations.

In this talk I will introduce the subject of Markov Chain Monte Carlo simulations to solve the path integral over geometries. This general introduction will use examples from Causal Dynamical Triangulations, Causal Set Theory and Non Commutative geometry to show how different issues can be explored in this manner.

James Quach, University of Tokyo

Gravitational Casimir Effect

I will derive the gravitonic Casimir effect with non-idealized boundary conditions. This allows the quantification of the gravitonic contribution to the Casimir effect from real bodies. I will show how to use this formula to calculate the meagre gravitonic Casimir effect in ordinary matter. I will also apply this formula to the speculated Heisenberg-Couloumb (HC) effect in superconductors, thereby providing a test for the validity of the HC theory, and, consequently, the existence of gravitons.

Erik Schnetter, Perimeter Institute

Efficient numerical methods for modern computing systems

Guifre Vidal, Perimeter Institute

Tensor network renormalization

I will present a pedagogical introduction on the application of tensor networks to the renormalization group. This program has resulted in a non-perturbative, real-space RG approach for lattice systems and the multi-scale entanglement renormalization ansatz (MERA). The MERA is currently of interest in a wide range of research areas, from statistical mechanics to condensed matter, from quantum field theory to holography in quantum gravity.

Jose Zapata, Universidad Nacional Autonoma de Mexico

Observable currents for effective field theories and their context

The primary objective of an effective field theory is modelling observables at the given scale. The subject of this talk is a notion of observable at a given scale in a context that does not rely on a metric background.

Within a geometrical formalism for local covariant effective field theories, a discrete version of the multisymplectic approach to lagrangian field theory, I introduce the notion of observable current. The pair of an observable current and a codimension one surface (f, \Sigma) yields an observable Q_{f, \Sigma} : Histories \to R . The defining property of observable currents is that if \phi \in Solutions \subset Histories and \Sigma’ - \Sigma = \partial B (for some region B) then Q_{f, \Sigma'} (\phi) = Q_{f, \Sigma} (\phi) . Thus, an observable current f is a local object which may use an ``auxiliary devise’’ \Sigma, relevant only up to homology, to induce functions on the space of solutions.

There is a Poisson bracket that makes the space of observable currents a Lie algebra. We construct observable currents and prove that solutions can be separated by evaluating the induced functions.

We comment on the relevance of this framework for covariant loop quantization.