Talks

10681 - 10692 of 16655 Results

Searching for Quantum Gravity with the IceCube Neutrino Observatory

John Kelley University of Wisconsin–Madison

October 23, 2012

PIRSA:12100093

Quantum Gravity
From Effective Strings to the Simplest theory of Quantum Gravity

October 23, 2012

PIRSA:12100040

Quantum Fields and Strings
New Results in Jet Substructure

October 23, 2012

PIRSA:12100128

Particle Physics
An informal discussion about topological gauge theory

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

October 23, 2012

PIRSA:12100129

Quantum Fields and Strings
Quantum Field Theory - Lecture 11B

Konstantin Zarembo Nordic Institute for Theoretical Physics

October 23, 2012

PIRSA:12100072

Quantum Fields and Strings
Condensed Matter - Lecture 11

Assa Auerbach Technion – Israel Institute of Technology

October 23, 2012

PIRSA:12100036

Condensed Matter
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 Sapienza Università di Roma - Dipartimento di Fisica

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

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).
From Effective Strings to the Simplest theory of Quantum Gravity

October 23, 2012

PIRSA:12100040

Quantum Fields and Strings

String-like objects arise in many quantum field theories. Well known examples include flux tubes in QCD and cosmic strings. To a first approximation, their dynamics is governed by the Nambu-Goto action, but for QCD flux tubes numerical calculations of the energy levels of these objects have become so accurate that a systematic understanding of corrections to this simple description is desirable. In the first part of my talk, I discuss an effective field theory describing long relativistic strings. The construction parallels that of the chiral Lagrangian in that it is based on the pattern of symmetry breaking. To compare with previous works, I will present the results of the calculation of the S-matrix describing the scattering of excitations on the string worldsheet. In the second part of my talk, I will discuss critical strings from the same point of view and show that the worldsheet S-matrix in this case is non-trivial but can be calculated exactly. I will show that it encodes the familiar square-root formula for the energy levels of the string, the Hagedorn behavior of strings, and argue that the theory on the string worldsheet behaves like a 1+1 dimensional theory of quantum gravity rather than a field theory. If time permits, I will return to the task of computing the energy levels of flux-tubes using lessons learned from the second part of my talk.
New Results in Jet Substructure

October 23, 2012

PIRSA:12100128

Particle Physics

We present new results on the performance of jet substructure techniques and their use in distinguishing the signatures of new boosted massive particles from the QCD background. Advanced approaches to jet reconstruction using jet grooming algorithms such as filtering, trimming, and pruning are compared. Measurements of the jet invariant mass for each jet algorithm are compared both at the particle level to multiple Monte Carlo event generators and at the detector level for several configurations of the jet grooming algorithms. The performance of these strategies and improvements in search sensitivity for new boosted hadronic particles are compared. Recent results using these techniques for both boosted RPV gluinos and top quark pairs from new particles are presented. The result is a comprehensive foundation for the use of substructure algorithms in the search for new physics at the LHC
An informal discussion about topological gauge theory

Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics

October 23, 2012

PIRSA:12100129

Quantum Fields and Strings

Reference:
Topological gauge theories and group cohomology
Robbert Dijkgraaf and Edward Witten
http://projecteuclid.org/DPubS?service=UI&version=1.0&verb=Display&handle=euclid.cmp/1104180750

Braiding statistics approach to symmetry-protected topological phases
Michael Levin, Zheng-Cheng Gu
http://arxiv.org/abs/1202.3120
Quantum Field Theory - Lecture 11B

Konstantin Zarembo Nordic Institute for Theoretical Physics

October 23, 2012

PIRSA:12100072

Quantum Fields and Strings
Condensed Matter - Lecture 11

Assa Auerbach Technion – Israel Institute of Technology

October 23, 2012

PIRSA:12100036

Condensed Matter
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 Sapienza Università di Roma - Dipartimento di Fisica

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

Title	Date	Collection	Type	Info
Searching for Quantum Gravity with the IceCube Neutrino Observatory	2012‑10‑23	Experimental Search for Quantum Gravity 2012	Conference	View details
From Effective Strings to the Simplest theory of Quantum Gravity	2012‑10‑23	Quantum Fields and Strings	Scientific Series	View details
New Results in Jet Substructure	2012‑10‑23	Particle Physics	Scientific Series	View details
An informal discussion about topological gauge theory	2012‑10‑23	Quantum Matter	Scientific Series	View details
Quantum Field Theory - Lecture 11B	2012‑10‑23	12/13 PSI - Quantum Field Theory 1	Course	View details
Condensed Matter - Lecture 11	2012‑10‑23	12/13 PSI - Condensed Matter	Course	View details
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

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