Experimental Search for Quantum Gravity 2012

17 talks

October 22, 2012 - October 25, 2012

C12043

Collection Type Conference/School

Description Experimental Search for Quantum Gravity

Displaying 1 - 12 of 17

Matter-wave clocks

Holger Mueller University of California, Berkeley
October 22, 2012
PIRSA:12100124
Quantum Gravity
Improved test of the Equivalence Principle as a probe of quantum gravity
- James Overduin Towson University
- Daniel Sudarsky Universidad Nacional Autónoma De Mexico (UNAM)
October 22, 2012
PIRSA:12100127
Quantum Gravity
Is there a MesoScale in Quantum Gravity? Is it a Non-Locality Scale?
- Laurent Freidel Perimeter Institute for Theoretical Physics
- Stefano Liberati SISSA International School for Advanced Studies
- Dionigi Benincasa
October 22, 2012
PIRSA:12100082
Quantum Gravity
Lorentz Invariance Violation searches with HESS

Julien Bolmont Sorbonne University

October 22, 2012
PIRSA:12100084
Photons and Quantum Gravity in Astrophysics
- Robert Nemiroff Michigan Technological University
- Giovanni Amelino-Camelia Sapienza Università di Roma - Dipartimento di Fisica
- Niayesh Afshordi University of Waterloo
- Joao Magueijo Imperial College London
- Alfio Bonanno National Institute for Astrophysics
- Robert Brandenberger McGill University - Department of Physics
October 22, 2012
PIRSA:12100085
Quantum Gravity

Particle Physics
The highest-energy particles of the Universe as viewed by the Pierre Auger Observatory

Markus Risse University of Siegen

October 23, 2012
PIRSA:12100089
Quantum Gravity Effects in the (Early and Late) Universe
- Stephon Alexander Brown University
- Daniel Sudarsky Universidad Nacional Autónoma De Mexico (UNAM)
- Daniel Litim University of Sussex
- Robert Brandenberger McGill University - Department of Physics
October 23, 2012
PIRSA:12100090
Quantum Gravity
Searching for Quantum Gravity with the IceCube Neutrino Observatory

John Kelley University of Wisconsin–Madison
October 23, 2012
PIRSA:12100093
Quantum Gravity
Quantum Gravity Effects in Black Holes and Gravitational Waves
- Giovanni Amelino-Camelia Sapienza Università di Roma - Dipartimento di Fisica
- David Mattingly University of New Hampshire
- Nicolas Yunes University of Illinois Urbana-Champaign
- Avery Broderick University of Waterloo
October 23, 2012
PIRSA:12100094
Quantum Gravity
Cosmological Constant
- Ivan Arraut University of Saint Joseph
- Stephon Alexander Brown University
- Alejandro Satz
- Maïté Dupuis Perimeter Institute for Theoretical Physics
- Antonino Marciano Fudan University
October 23, 2012
PIRSA:12100126
Cosmology
Dynamical Dimensional Reduction
- Dejan Stojkovic State University of New York (SUNY)
- Astrid Eichhorn University of Southern Denmark
- Martin Reuter Johannes Gutenberg University Mainz
October 24, 2012
PIRSA:12100104
Quantum Gravity
Astrophysical Searches for Quantum Gravity Signals

Jonathan Granot University of Hertfordshire
October 24, 2012
PIRSA:12100058
Quantum Gravity

Matter-wave clocks

Holger Mueller University of California, Berkeley
October 22, 2012
PIRSA:12100124
Quantum Gravity
Improved test of the Equivalence Principle as a probe of quantum gravity
- James Overduin Towson University
- Daniel Sudarsky Universidad Nacional Autónoma De Mexico (UNAM)
October 22, 2012
PIRSA:12100127
Quantum Gravity
Current approaches to the problems of dark energy and unification generically predict the existence of new fields (quintessence dilatons etc.) that will in principle couple with different strengths to different standard-model fields. These different coupling strengths will cause test materials of different compositions to fall at different rates in the same gravitational field violating the Equivalence Principle the foundation of General Relativity. A sufficiently sensitive measurement of the relative accelerations of different test bodies in orbit around the earth could detect or rule out these new fields complementing existing or proposed experiments in high-energy physics (colliders) and observational cosmology (space telescopes). To do this convincingly such an experiment needs at least three test materials spanning the largest possible volume in the space of atomic and molecular properties and a sensitivity to EP violations of as little as a part in $10^{18}$ (attainable only in space and at low temperatures). I discuss one such experiment the Satellite Test of the Equivalence Principle which has reached an advanced stage of prototype development and is currently awaiting a path toward a flight program.
Is there a MesoScale in Quantum Gravity? Is it a Non-Locality Scale?
- Laurent Freidel Perimeter Institute for Theoretical Physics
- Stefano Liberati SISSA International School for Advanced Studies
- Dionigi Benincasa
October 22, 2012
PIRSA:12100082
Quantum Gravity
Lorentz Invariance Violation searches with HESS

Julien Bolmont Sorbonne University

October 22, 2012
PIRSA:12100084

The high flux and variability of the blazar PKS 2155-304 as observed by H.E.S.S. during the night of 28 July 2006 allowed a very high precision search for Quantum Gravity-induced energy-dependent time lags. In this talk, I will review the results published by the H.E.S.S. collaboration on this topic. In particular, I will emphasize the latest results obtained using a likelihood fit to study individual photon data. With this method and a proper error calibration procedure, a very high precision measurement was achieved leading to the best constraints on linear and quadratic terms of the dispersion relations obtained with an AGN so far.
Photons and Quantum Gravity in Astrophysics
- Robert Nemiroff Michigan Technological University
- Giovanni Amelino-Camelia Sapienza Università di Roma - Dipartimento di Fisica
- Niayesh Afshordi University of Waterloo
- Joao Magueijo Imperial College London
- Alfio Bonanno National Institute for Astrophysics
- Robert Brandenberger McGill University - Department of Physics
October 22, 2012
PIRSA:12100085
Quantum Gravity

Particle Physics
Asymptotically safe inflation and CMB polarization
The presence of complex critical exponents in the scaling behavior of the Newton constant and Cosmological constant has dramatic consequences at the inflation scale. In particular an infinite number of unstable de-Sitter vacua emerges from an effective quantum gravitational action. In this framework, the possibility of detecting specific signaturesof a non-gaussian fixed point of the gravitational interactions in the CMB polarization spectrum will then be discussed.

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Cosmological windows such as CMB polarization and 21cm redshift surveys to probe Planck-scale physics

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Quantum gravity and a chiral signature in gravity waves
I show how quantum gravity could lead to a chiral signature in the graviational wave background, proportional to the imaginary part of the Immirzi parameter. This would leave a distinctive imprint in the polarization of the cosmic microwave background. I will discuss how this isue is closely related to that of identifying the ground of base state for quantum gravity.

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A Possible Bound on Spectral Dispersion from Fermi-Detected Gamma Ray Burst 090510A
Three photons spanning about 30 GeV arrived within about one millisecond from the Fermi-detected GRB 090510A at a redshift of about 0.9. Although conceivably a > 3Ïƒ statistical fluctuation when taken at face value this photon bunch -- quite possibly a classic GRB pulse -- leads to a relatively tight bound on the ability of our universe to disperse high energy photons. Specifically given a generic dispersion relation where the time delay is proportional to the photon energy to the first power the limit on the dispersion strength is k1 < 1.61Ã—10-5 sec Gpc-1 GeV-1. In the context of some theories of quantum gravity this conservative bound translates into an minimum energy scale greater than 525 m_Planck suggesting that spacetime is smooth at energies perhaps three orders of magnitude over the Planck mass.
The highest-energy particles of the Universe as viewed by the Pierre Auger Observatory

Markus Risse University of Siegen

October 23, 2012
PIRSA:12100089

One century after the seminal balloon flights of Victor Hess, the Pierre Auger Observatory aims at unveiling some of the mysteries of the highest-energy cosmic rays: what are their sources? Is there an end to the spectrum? What kind of particles are they? Are there signatures of new physics or of a violation of fundamental laws of physics? The Auger Observatory measures cosmic rays with energies of 10^20 eV or more by observing the giant air showers created when the particles hit the atmosphere. Located in Argentina, two complementary detector systems are used: an array of 1600 water-Cherenkov detectors distributed over 3000 sqkm, and fluorescence telescopes which monitor the atmosphere above the array in clear nights. Since 2005, data of unprecedented quantity and quality could be taken. In the talk, the observation principles, successes and limitations are described. Current, partly surprising results are presented. Data interpretations related to the search for violation of Lorentz invariance are mentioned.
Quantum Gravity Effects in the (Early and Late) Universe
- Stephon Alexander Brown University
- Daniel Sudarsky Universidad Nacional Autónoma De Mexico (UNAM)
- Daniel Litim University of Sussex
- Robert Brandenberger McGill University - Department of Physics
October 23, 2012
PIRSA:12100090
Quantum Gravity
Quantum Gravity at the origin of seeds of cosmic structure?
This meeting shows a our impatience for uncovering at long last any signal of unknown physics that might have a quantum gravitational origin. I will argue that the transition from a homogenous and isotropic state characterizing the mid-early parts of inflation ( i.e. the regime after sufficient e- folds of inflation have elapsed so that all traces of the pre-inflationary state are erased), to those eras, where the primordial inhomogeneities have appears might hold ins testing clues about the nature of quantum gravity

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Quantum gravity and cosmology
In the light of upcoming high-precision data from the Planck mission and possible trans-Planckian signatures encoded in eg the microwave background radiation, and in view of possible large-distance modifications of gravity and the accelearted expansion of the universe
Searching for Quantum Gravity with the IceCube Neutrino Observatory

John Kelley University of Wisconsin–Madison
October 23, 2012
PIRSA:12100093
Quantum Gravity
The IceCube Neutrino Observatory is a cubic-kilometer-scale neutrino detector built into the ice sheet at the geographic South Pole. Completed in December 2010, the detector consists of an array of photomultiplier tubes deployed along 86 cables ("strings") at depths of 1450 to 2450 m, as well as the IceTop air shower array of surface Cherenkov tanks. IceCube is detecting atmospheric neutrinos of energies above approximately 100 GeV at a rate of ~6 per hour, and is currently searching for extraterrestrial neutrinos from cosmic ray accelerators. A measurement of the atmospheric neutrino spectrum can be used to search for possible phenomenological signatures of quantum gravity (QG), such as violations of Lorentz invariance or quantum decoherence, and I present limits we have set on these phenomena in the neutrino sector. To extend the search for QG to much higher energies and cosmological baselines, we require an extraterrestrial neutrino source. In this context, I report on the status of our searches for neutrinos from gamma-ray bursts and from cosmic-ray interactions with the microwave background ("cosmogenic" neutrinos).
Quantum Gravity Effects in Black Holes and Gravitational Waves
- Giovanni Amelino-Camelia Sapienza Università di Roma - Dipartimento di Fisica
- David Mattingly University of New Hampshire
- Nicolas Yunes University of Illinois Urbana-Champaign
- Avery Broderick University of Waterloo
October 23, 2012
PIRSA:12100094
Quantum Gravity
Quantum-gravity effects as noise for gravity-wave detectors
I discuss a mechanism that can allow Planck scale effects to manifest themselves as a source of lof-frequency noise for interferometers. The mechanism requires a discrete formulation of dynamics at the Planck scale.
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Dancing in the Dark: Images of Quantum Black Holes
There have recently been a number of rather surprising suggestions that the quantum nature of black holes is manifested on macroscopic scales. This raises the question of just what the image of such an object should look like. The answer is more than simply academic; with the advent of the Event Horizon Telescope (EHT), a millimetre-wave very long baseline array, it is now possible to probe a handful of supermassive black holes with angular resolutions sufficient to image their horizons. I will discuss what we might expect to see, and how in the near future we will begin to empirically probe the existence of black hole quantum states with horizon scale curvature deviations from general relativity.
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The Irritating Persistence of Horizons
In some approaches to quantum gravity Lorentz invariance is modified. Without Lorentz invariance one can theoretically see behind the usual Killing horizon of a black hole if, for example, one allowed for superluminal propagation. This in turn raises the possibility that one could in principle probe the singularity and the quantum gravity regime. We discuss how Lorentz violating black hole solutions in Einstein-aether theory unfortunately possess another causal boundary behind the Killing horizon that is impenetrable to any superluminal mode. We also detail progress in determining the laws of black hole mechanics and the radiation spectrum from these so-called "universal horizons". Our results suggest that even if superluminal dispersion at high frequencies did exist in nature, singularities and their associated quantum gravity resolutions may very well remain locked behind horizons.
Cosmological Constant
- Ivan Arraut University of Saint Joseph
- Stephon Alexander Brown University
- Alejandro Satz
- Maïté Dupuis Perimeter Institute for Theoretical Physics
- Antonino Marciano Fudan University
October 23, 2012
PIRSA:12100126
Cosmology
Dark Matter and Dark Energy as a Possible Manifestation of a Fundamental Scale
If we take the idea of the Planck length as a fundamental (minimum) scale and if additionally we impose the Cosmological Constant ($Lambda$) as and infrared (IR) cut-off parameter. Then it is possible to demonstrate that Dark Matter effects can emerge as a consequence of an IR-UV mix effect. This opens the possibility of unifying the Dark Energy and Dark matter effects in a single approach.

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Geometric Operators in Loop Quantum Gravity with a Cosmological Constant
Loop quantum gravity is a candidate to describe the quantum gravity regime with zero cosmological constant. One of its key results is that geometric operators such as area angle volume are quantized. Not much is known when the cosmological constant is not zero. It is usually believed that to introduce this parameter in the game we need to use quantum groups. However due to the complicated algebraic structure inherent to quantum groups the geometric operators are not yet properly defined (except the area operator). I will discuss how the use of tensor operators can circumvent the difficulties and allow to construct a natural set of observables. In particular I will construct the natural geometric observables such as angle or volume and discuss some of their implications.

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Interplay Between Cosmological Constant and DSR Scale
I offer brief remarks on several ways in which the cosmological constant could provide a clue toward quantum gravity. I then focus on how DSR-relativistic theories can be made compatible with spacetime expansion (possibly cosmological-constant-governed spacetime expansion), and how this interplay could manifest itself in data.

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Quantum Gravity RG Flow: A Cosmological Limit Cycle
I will discuss evidence for the existence of a limit cycle in the renormalization group for quantum gravity which is visible in a minisuperspace approximation. The emergence of the limit cycle can be studied through a tuning parameter representing the number of dimensions in which fluctuations of the conformal factor are suppressed. At the critical value of the tuning parameter all RG trajectories reaching the UV fixed point have an extended semiclassical regime with a small positive cosmological constant providing a possible model for a viable cosmology without fine-tuning.
Dynamical Dimensional Reduction
- Dejan Stojkovic State University of New York (SUNY)
- Astrid Eichhorn University of Southern Denmark
- Martin Reuter Johannes Gutenberg University Mainz
October 24, 2012
PIRSA:12100104
Quantum Gravity
Dynamical dimensional reduction and Asymptotic Safety
The effective average action approach to Quantum Einstein Gravity (QEG) is discussed as a natural framework for exploring the scale dependent Riemannian geometry and multifractal micro-structure of the effective spacetimes predicted by QEG. Their fractal properties are related to the functional RG flow on theory space, and the special role of the running cosmological constant is emphasized. The prospects of an experimental verification will also be discussed.
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Vanishing dimension: theory and phenomenology
Lower-dimensionality at higher energies has manifold theoretical advantages as recently pointed out. Moreover, it appears that experimental evidence may already exists for it - a statistically significant planar alignment of events with energies higher than TeV has been observed in some earlier cosmic ray experiments. If this alignment is not a fluke, then the LHC should be able to see effects associated with the dimensional crossover. Further, (2+1)-dimensional spacetimes have no gravitational degrees of freedom, and gravity waves cannot be produced in that epoch in the early universe. This places a universal maximum frequency at which primordial gravity waves can propagate, which may be accessible to future gravitational wave detectors such as LISA. In this talk, the theoretical motivation for "vanishing dimensions" as well as generic experimental and observational signature will be discussed
Astrophysical Searches for Quantum Gravity Signals

Jonathan Granot University of Hertfordshire
October 24, 2012
PIRSA:12100058
Quantum Gravity
Some recent searches for quantum gravity signatures using observations of distant astrophysical sources will be discussed, focusing on the search for Lorentz invariance violation (LIV) in the form of a dependence of the photon propagation speed on its energy. Fermi gamma-ray space telescope observations of ~8 keV to ~30 GeV photons from a short (< 1 s) gamma-ray burst (GRB 090510) at a cosmological distance (z = 0.903), enabled for the first time to put a direct time of flight limit on a possible linear variation of the speed of light with photon energy that is beyond the Planck scale. Parameterizing |v/c-1| = E/E_{QG} our most conservative limits are E_{QG}/E_{Planck} > 1.2, while less conservative limits are up to 1-2 orders of magnitude stricter. Other types of astrophysical searches for LIV will be briefly outlined, along with some prospects for the future.

Title	Speaker(s)	Date	Talk Type	Info
Matter-wave clocks	Holger Mueller	2012-10-22	Conference	View details
Improved test of the Equivalence Principle as a probe of quantum gravity	James Overduin, Daniel Sudarsky	2012-10-22	Conference	View details
Is there a MesoScale in Quantum Gravity? Is it a Non-Locality Scale?	Laurent Freidel, Stefano Liberati, Dionigi Benincasa	2012-10-22	Conference	View details
Lorentz Invariance Violation searches with HESS	Julien Bolmont	2012-10-22	Conference	View details
Photons and Quantum Gravity in Astrophysics	Robert Nemiroff, Giovanni Amelino-Camelia, Niayesh Afshordi, Joao Magueijo, Alfio Bonanno, Robert Brandenberger	2012-10-22	Conference	View details
The highest-energy particles of the Universe as viewed by the Pierre Auger Observatory	Markus Risse	2012-10-23	Conference	View details
Quantum Gravity Effects in the (Early and Late) Universe	Stephon Alexander, Daniel Sudarsky, Daniel Litim, Robert Brandenberger	2012-10-23	Conference	View details
Searching for Quantum Gravity with the IceCube Neutrino Observatory	John Kelley	2012-10-23	Conference	View details
Quantum Gravity Effects in Black Holes and Gravitational Waves	Giovanni Amelino-Camelia, David Mattingly, Nicolas Yunes, Avery Broderick	2012-10-23	Conference	View details
Cosmological Constant	Ivan Arraut, Stephon Alexander, Alejandro Satz, Maïté Dupuis, Antonino Marciano	2012-10-23	Conference	View details
Dynamical Dimensional Reduction	Dejan Stojkovic, Astrid Eichhorn, Martin Reuter	2012-10-24	Conference	View details
Astrophysical Searches for Quantum Gravity Signals	Jonathan Granot	2012-10-24	Scientific Series	View details

Experimental Search for Quantum Gravity 2012

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