Experimental Search for Quantum Gravity: the hard facts

Quantum Gravity tries to answer some of the most fundamental questions about the quantum nature of spacetime. To make progress in this area it is mandatory to establish a contact to observations and experiments and to learn what the "hard facts" on quantum gravity are, that nature provides us with.

Quantum Gravity is a field where several approaches, based on different principles and assumptions, develop in parallel. At present it is not clear whether and how some of the approaches are compatible, and might share common properties. This meeting will draw on a diverse set of physicists who come to make proposals for quantum gravity phenomenology from a broad range of perspectives, including path-integral-inspired as well as canonical, and discrete as well as continuum-based approaches, providing a platform to exchange ideas with researchers working on theoretical and experimental aspects of different proposals.

This will be the third in a series of meetings, the first of which was held at PI (2007), the second at NORDITA (2010).

This meeting looks to the future and has two primary goals: 1) to assess the status of different proposals for QG phenomenology in the light of recent experimental results from Fermi, Auger, LHC etc. and 2) to discuss and stimulate new ideas and proposals, coming from a diverse set of viewpoints about quantum spacetime.

In order to allow for a fruitful exchange of ideas across different approaches, and between experimental and theoretical researchers, the workshop will lay a main focus on structured discussion sessions with short (15 min.) presentations. These are mainly intended for an exchange of ideas, and a discussion and development of new possibilities, thus participants are strongly encouraged to present new ideas and work in progress.

NEW EXPERIMENTAL IDEAS:

• GRBs, TeV photons, high-energy cosmic rays (threshold anomalies, time delay measurements, polarisation effects)
• How can we use a future linear collider to search for quantum gravity effects? (What motivation do we have to consider extra dimensions above the electroweak scale? Can we access quantum gravity effects in precision measurements?)
• Quantum gravity and ultracold atoms (Can we see granular spacetime with ultracold atoms? Do we understand QM and classical gravity? Can we "test" Hawking radiation with ions, BECs...)
• Quantum gravity at high-intensity lasers (Light-shining-through-a-wall experiments, quantum gravity effects in photon-photon scattering, modified dispersion relation tests, analogue Hawking radiation with ultrashort laser pulses)
• Perspectives for quantum gravity effects in gravitational waves. (How can we see "graviton" effects in gravitational waves? Can we see a scale-or time- dependent Newton coupling?)

THEORETICAL IDEAS:

• Discrete vs. continuous (How can we decide the question discrete/non-discrete experimentally? Is this a physically meaningful distinction, or is it just a distinction at the level of the description? Does a minimal spatial or spacetime length exist? What is the status of symmetries in discrete approaches? How does singularity resolution work in discrete/continuum approaches?)
• Is there a mesoscale in quantum gravity? (What are possible experimental manifestations? Is it a non-locality scale?)
• Dynamical dimensional reduction (Is the transition to 2 dimensions generic? Is it measurable? How does it affect the dynamics of particles? Is spacetime fractal? If so, what kind of fractal and what are the implications for quantum field theory calculations at small scales?)
• Lorentz-symmetry: Intact, broken or deformed? What are new phenomenological implications of each case? What is the status of fundamental symmetries in quantum gravity? Quantum gravity effects in the effective-field theory framework: How can we use the Renormalisation Group to access quantum gravity effects? What is the precise relation of the effective-field theory framework to different quantum gravity approaches? What are the fundamental variables to use?
• The cosmological constant (Is it a UV or an IR problem? Is there a particle-physics solution? Is unimodular quantum gravity a viable solution? Does Lambda "run"? What are the experimental bounds on a time-dependent Lambda?)

Participants:

Niayesh Afshordi, Perimeter Institute
Stephon Alexander, Haverford College and Pennsylvania State University
Giovanni Amelino-Camelia, University of Rome
Ivan Arraut, Osaka University
James Bardeen, University of Washington, Seattle
Hugo Beauchemin, Tufts University
Dario Benedetti, Albert Einstein Institute
Dionigi Benincasa, Imperial College, London
Eugenio Bianchi, Perimeter Institute
Julien Bolmont, Pierre and Marie Curie University
Alfio Bonanno, INAF Catania Astrophysical Observatory
Robert Brandenberger, McGill University
Avery Broderick, Perimeter Institute
Xavier Calmet, University of Sussex
Antonio Di Domenico, University of Rome
Bianca Dittrich, Perimeter Institute
Astrid Eichhorn, Perimeter Institute
Laurent Freidel, Perimeter Institute
Tobias Fritz, Perimeter Institute
Steffen Gielen, Perimeter Institute
Doug Gingrich, University of Alberta
Florian Girelli, University of Waterloo
Jonathan Granot, University of Hertfordshire
Sabine Hossenfelder, NORDITA
Drew Jamieson, University of Guelph
Oleg Kabernik, University of Waterloo
John Kelley, University of Wisconsin-Madison
Jurek Kowalski-Glikman, Institute for Theoretical Physics
Stefano Liberati, SISSA
Daniel Litim, University of Sussex
Joao Magueijo, Imperial College, London
Anson Maitland, University of Waterloo
Seth Major, Hamilton College
David Matthingly, University of New Hampshire
John Moffat, Perimeter Institute
Holger Mueller, University of California, Berkeley
Robert Nemiroff, Michigan Technological University
Daniele Oriti, Max Planck Institute for Gravitational Physics
James Overduin, Towson University
Roberto Percacci, SISSA
Martin Reuter, University of Mainz
Markus Risse, University of Siegen
Alejandro Satz, University of Maryland
Giuseppe Sellaroli, University of Waterloo
Lorenzo Sindoni, Max Planck Institute for Gravitational Physics
Lee Smolin, Perimeter Institute
Fabrizio Sorba, Karlsruhe Institute of Technology
Sebastian Steinhaus, Perimeter Institute
Dejan Stojkovic, SUNY
Daniel Surdarsky, Universidad Nacional Autonoma de Mexico
Giovanni Venturi, University di Bologna
Cameron Williams, University of Waterloo
Nicolas Yunes, University of Montana
Jonathan Ziprick, Perimeter Institute