Talks

10921 - 10932 of 16889 Results

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 Field Theory - Lecture 11A

Konstantin Zarembo Nordic Institute for Theoretical Physics

October 23, 2012

PIRSA:12100018

Quantum Fields and Strings
The highest-energy particles of the Universe as viewed by the Pierre Auger Observatory

Markus Risse University of Siegen

October 23, 2012

PIRSA:12100089
Photons and Quantum Gravity in Astrophysics

Robert Nemiroff Michigan Technological University

Giovanni Amelino-Camelia University of Naples Federico II

Niayesh Afshordi University of Waterloo

Joao Magueijo Imperial College London

Alfio Bonanno National Institute for Astrophysics (INAF)

Robert Brandenberger McGill University - Department of Physics

October 22, 2012

PIRSA:12100085

Quantum Gravity

Particle Physics
Lorentz Invariance Violation searches with HESS

Julien Bolmont Sorbonne University

October 22, 2012

PIRSA:12100084
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
The cosmological constant and the emergence of the continuum

Lorenzo Sindoni Max Planck Institute for Gravitational Physics - Albert Einstein Institute (AEI)

October 22, 2012

PIRSA:12100081

Cosmology
An analogue model lesson for the cosmological constant

Stefano Liberati SISSA International School for Advanced Studies

October 22, 2012

PIRSA:12100080

Cosmology
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
Quantum Field Theory - Lecture 10B

Konstantin Zarembo Nordic Institute for Theoretical Physics

October 22, 2012

PIRSA:12100071

Quantum Fields and Strings
Condensed Matter - Lecture 10

Assa Auerbach Technion – Israel Institute of Technology

October 22, 2012

PIRSA:12100035

Condensed Matter
Matter-wave clocks

Holger Mueller University of California, Berkeley

October 22, 2012

PIRSA:12100124

Quantum Gravity

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
Quantum Field Theory - Lecture 11A

Konstantin Zarembo Nordic Institute for Theoretical Physics

October 23, 2012

PIRSA:12100018

Quantum Fields and Strings
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.
Photons and Quantum Gravity in Astrophysics

Robert Nemiroff Michigan Technological University

Giovanni Amelino-Camelia University of Naples Federico II

Niayesh Afshordi University of Waterloo

Joao Magueijo Imperial College London

Alfio Bonanno National Institute for Astrophysics (INAF)

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.
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.
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
The cosmological constant and the emergence of the continuum

Lorenzo Sindoni Max Planck Institute for Gravitational Physics - Albert Einstein Institute (AEI)

October 22, 2012

PIRSA:12100081

Cosmology

Naturalness problems that could be signaling the necessity a completion of an effective field theory with the introduction of an otherwise overlooked ingredient. The cosmological constant problem can be seen as a signal that the EFT for gravity, general relativity, is not correctly including the gravitational properties of the vacuum. Starting from the discussion of the a possible solution to this naturalness problem for a cc-like term in a BEC analogue model, I will briefly discuss how this particular mechanism can be extended, albeit in a preliminary form, to more genuine quantum gravity models like GFT, connecting in particular the problem of the determination of the gravitational couplings (and hence the hierarchies involved) to the appearance of a semiclassical space-time
An analogue model lesson for the cosmological constant

Stefano Liberati SISSA International School for Advanced Studies

October 22, 2012

PIRSA:12100080

Cosmology

Analogue models of gravity have been a test field for many phenomena in quantum field theory on curved spacetimes. It was recently recognized that in some situations they can also provide toy models of emergent gravity. We shall review here such a model and address within it the nature and scale of the cosmological constrant trying to draw general lessons for emergent gravity scenarios.
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.
Quantum Field Theory - Lecture 10B

Konstantin Zarembo Nordic Institute for Theoretical Physics

October 22, 2012

PIRSA:12100071

Quantum Fields and Strings
Condensed Matter - Lecture 10

Assa Auerbach Technion – Israel Institute of Technology

October 22, 2012

PIRSA:12100035

Condensed Matter
Matter-wave clocks

Holger Mueller University of California, Berkeley

October 22, 2012

PIRSA:12100124

Quantum Gravity

Title	Date	Collection	Type	Info
Quantum Gravity Effects in the (Early and Late) Universe	2012‑10‑23	Experimental Search for Quantum Gravity 2012	Conference	View details
Quantum Field Theory - Lecture 11A	2012‑10‑23	12/13 PSI - Quantum Field Theory 1	Course	View details
The highest-energy particles of the Universe as viewed by the Pierre Auger Observatory	2012‑10‑23	Experimental Search for Quantum Gravity 2012	Conference	View details
Photons and Quantum Gravity in Astrophysics	2012‑10‑22	Experimental Search for Quantum Gravity 2012	Conference	View details
Lorentz Invariance Violation searches with HESS	2012‑10‑22	Experimental Search for Quantum Gravity 2012	Conference	View details
Is there a MesoScale in Quantum Gravity? Is it a Non-Locality Scale?	2012‑10‑22	Experimental Search for Quantum Gravity 2012	Conference	View details
The cosmological constant and the emergence of the continuum	2012‑10‑22	Experimental Search for Quantum Gravity 2007	Conference	View details
An analogue model lesson for the cosmological constant	2012‑10‑22	Experimental Search for Quantum Gravity 2007	Conference	View details
Improved test of the Equivalence Principle as a probe of quantum gravity	2012‑10‑22	Experimental Search for Quantum Gravity 2012	Conference	View details
Quantum Field Theory - Lecture 10B	2012‑10‑22	12/13 PSI - Quantum Field Theory 1	Course	View details
Condensed Matter - Lecture 10	2012‑10‑22	12/13 PSI - Condensed Matter	Course	View details
Matter-wave clocks	2012‑10‑22	Experimental Search for Quantum Gravity 2012	Conference	View details

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