Talks

11281 - 11292 of 19186 Results

13/14 PSI - Condensed Matter - Lecture 4

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

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

November 14, 2013

PIRSA:13110030
13/14 PSI - Quantum Field Theory II - Lecture 4

Francois David CEA Saclay

November 14, 2013

PIRSA:13110011
Bulk-boundary correspondence in PEPS

Ignacio Cirac Max Planck Institute for Gravitational Physics - Albert Einstein Institute (AEI)

November 13, 2013

PIRSA:13110058

Quantum Physics
Spin and Long-Range Forces: The Unfinished Tale of the Last Massless Particle

Natalia Toro Stanford University

November 13, 2013

PIRSA:13110047

High Energy Physics
13/14 PSI - Condensed Matter - Lecture 3

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

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

November 13, 2013

PIRSA:13110029
13/14 PSI - Quantum Field Theory II - Lecture 3

Francois David CEA Saclay

November 13, 2013

PIRSA:13110010
General Relativity for Cosmology - Lecture 17

Achim Kempf University of Waterloo

November 12, 2013

PIRSA:13110001
Quantum mechanics as an operationally time symmetric probabilistic theory

Ognyan Oreshkov Université Libre de Bruxelles

November 12, 2013

PIRSA:13110057

Quantum Physics
On Scale and Conformal Invariance in Four Dimensions

Anatoly Dymarsky Skolkovo Institute of Science and Technology

November 12, 2013

PIRSA:13110068

High Energy Physics
Baryogenesis from WIMPs

November 12, 2013

PIRSA:13110046

High Energy Physics
Is there evidence for additional neutrino species from cosmology?

Stephen Feeney

November 12, 2013

PIRSA:13110083

Astrophysics
13/14 PSI - Condensed Matter - Lecture 2

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

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

November 12, 2013

PIRSA:13110028

13/14 PSI - Condensed Matter - Lecture 4

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

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

November 14, 2013

PIRSA:13110030
13/14 PSI - Quantum Field Theory II - Lecture 4

Francois David CEA Saclay

November 14, 2013

PIRSA:13110011
Bulk-boundary correspondence in PEPS

Ignacio Cirac Max Planck Institute for Gravitational Physics - Albert Einstein Institute (AEI)

November 13, 2013

PIRSA:13110058

Quantum Physics

TBA
Spin and Long-Range Forces: The Unfinished Tale of the Last Massless Particle

Natalia Toro Stanford University

November 13, 2013

PIRSA:13110047

High Energy Physics

The success of gauge theory descriptions of Nature follows simply, in hindsight, from Lorentz symmetry, quantum mechanics, and the existence of interacting massless particles with spin. Yet, remarkably, the most generic type of massless particle spin has never been seriously examined: Wigner's so-called "continuous spin" particles (CSPs), which have a tower of polarization states carrying all integer or half-integer helicities that mix under boosts. I will explain recent progress in understanding these particles on two fronts: simple scattering amplitudes and a free quantum field theory. The scattering amplitudes give two remarkable insights into CSP physics. First, Lorentz symmetry protects CSP interactions from the dysfunction one might expect in a theory with infinitely many polarization states: divergent cross-sections and problematic thermodynamics. Second, and most intriguingly, CSP interactions approach those of ordinary scalars or helicity-1 or 2 gauge bosons in a high-energy "correspondence" regime. While a full interacting theory of CSPs remains elusive, these results suggest that any such theory would extend Maxwell electrodynamics and/or general relativity in a viable and testable way.
13/14 PSI - Condensed Matter - Lecture 3

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

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

November 13, 2013

PIRSA:13110029
13/14 PSI - Quantum Field Theory II - Lecture 3

Francois David CEA Saclay

November 13, 2013

PIRSA:13110010
General Relativity for Cosmology - Lecture 17

Achim Kempf University of Waterloo

November 12, 2013

PIRSA:13110001
Quantum mechanics as an operationally time symmetric probabilistic theory

Ognyan Oreshkov Université Libre de Bruxelles

November 12, 2013

PIRSA:13110057

Quantum Physics

The standard formulation of quantum mechanics is operationally asymmetric with respect to time reversal---in the language of compositions of tests, tests in the past can influence the outcomes of test in the future but not the other way around. The question of whether this represents a fundamental asymmetry or it is an artifact of the formulation is not a new one, but even though various arguments in favor of an inherent symmetry have been made, no complete time-symmetric formulation expressed in rigorous operational terms has been proposed. Here, we discuss such a possible formulation based on a generalization of the usual notion of test. We propose to regard as a test any set of events between an input and an output system which can be obtained by an autonomously defined laboratory procedure. This includes standard tests, as well as proper subsets of the complete set of outcomes of standard tests, whose realization may require post-selection in addition to pre-selection. In this approach, tests are not expected to be operations that are up to the choices of agents---the theory simply says what circuits of tests may occur and what the probabilities for their outcomes would be, given that they occur. By virtue of the definition of test, the probabilities for the outcomes of past tests can depend on tests that take place in the future. Such theories have been previously called non-causal, but here we revisit that notion of causality. Using the Choi-Jamiolkowski isomorphism, every test in that formulation, commonly regarded as inducing transformations from an input to an output system, becomes equivalent to a passive detection measurement applied jointly on two input systems---one from the past and one from the future. This is closely related to the two-state vector formalism, but it comes with a conceptual revision: every measurement is a joint measurement on two separate systems and not on one system described by states in the usual Hilbert space and its dual. We thus obtain a static picture of quantum mechanics in space-time or more general structures, in which every experiment is a local measurement on a global quantum state that generalizes the recently proposed quantum process matrix. The existence of two types of systems in the proposed formalism allows us to define causation in terms of correlations without invoking the idea of intervention, offering a possible answer to the problem of the meaning of causation. The framework is naturally compatible with closed time-like curves and other exotic causal structures.
On Scale and Conformal Invariance in Four Dimensions

Anatoly Dymarsky Skolkovo Institute of Science and Technology

November 12, 2013

PIRSA:13110068

High Energy Physics

I will be discussing relation between scale and conformal symmetry in unitary Lorentz invariant QFTs in four dimensions.
Baryogenesis from WIMPs

November 12, 2013

PIRSA:13110046

High Energy Physics

We propose a robust, unified framework, in which the similar baryon and dark matter cosmic abundances both arise from the physics of weakly interacting massive particles (WIMPs), with the rough quantitative success of the so-called “WIMP miracle”. In particular the baryon asymmetry arises from the decay of a meta-stable WIMP after its thermal freezeout at or below the weak scale. A minimal model and its embedding in R-parity violating (RPV) natural SUSY are studied as examples. The new mechanism saves RPV SUSY from the potential crisis of washing out primordial baryon asymmetry. We also consider the embedding of this idea in RPV split SUSY, where the mechanism works within the minimal model, and independently motivates the mini-split scale. Phenomenological implications for the LHC and precision tests are discussed.
Is there evidence for additional neutrino species from cosmology?

Stephen Feeney

November 12, 2013

PIRSA:13110083

Astrophysics

It has been suggested that recent cosmological and flavor-oscillation data favor the existence of additional neutrino species beyond the three standard flavors. We apply Bayesian model selection to determine whether there is any evidence from current cosmological datasets for the standard cosmological model to be extended to include additional neutrino flavors. The datasets employed include cosmic microwave background temperature, polarization and lensing data, and measurements of the baryon acoustic oscillation scale and the Hubble constant. We also consider other additional neutrino physics, such as massive neutrinos, and possible degeneracies with other cosmological parameters.
13/14 PSI - Condensed Matter - Lecture 2

Anushya Chandran Perimeter Institute for Theoretical Physics

Roger Melko University of Waterloo

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

November 12, 2013

PIRSA:13110028

Title	Date	Collection	Type	Info
13/14 PSI - Condensed Matter - Lecture 4	2013‑11‑14	13/14 PSI - Condensed Matter	Course	View details
13/14 PSI - Quantum Field Theory II - Lecture 4	2013‑11‑14	13/14 PSI - Quantum Field Theory II	Course	View details
Bulk-boundary correspondence in PEPS	2013‑11‑13	Perimeter Institute Quantum Discussions	Scientific Series	View details
Spin and Long-Range Forces: The Unfinished Tale of the Last Massless Particle	2013‑11‑13	Colloquium	Scientific Series	View details
13/14 PSI - Condensed Matter - Lecture 3	2013‑11‑13	13/14 PSI - Condensed Matter	Course	View details
13/14 PSI - Quantum Field Theory II - Lecture 3	2013‑11‑13	13/14 PSI - Quantum Field Theory II	Course	View details
General Relativity for Cosmology - Lecture 17	2013‑11‑12	General Relativity for Cosmology - 2013	Course	View details
Quantum mechanics as an operationally time symmetric probabilistic theory	2013‑11‑12	Quantum Foundations	Scientific Series	View details
On Scale and Conformal Invariance in Four Dimensions	2013‑11‑12	Quantum Fields and Strings	Scientific Series	View details
Baryogenesis from WIMPs	2013‑11‑12	Particle Physics	Scientific Series	View details
Is there evidence for additional neutrino species from cosmology?	2013‑11‑12	Cosmology and Gravitation	Scientific Series	View details
13/14 PSI - Condensed Matter - Lecture 2	2013‑11‑12	13/14 PSI - Condensed Matter	Course	View details

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Format results

13/14 PSI - Condensed Matter - Lecture 4

13/14 PSI - Quantum Field Theory II - Lecture 4

Bulk-boundary correspondence in PEPS

Spin and Long-Range Forces: The Unfinished Tale of the Last Massless Particle

13/14 PSI - Condensed Matter - Lecture 3

13/14 PSI - Quantum Field Theory II - Lecture 3

General Relativity for Cosmology - Lecture 17

Quantum mechanics as an operationally time symmetric probabilistic theory

On Scale and Conformal Invariance in Four Dimensions

Baryogenesis from WIMPs

Is there evidence for additional neutrino species from cosmology?

13/14 PSI - Condensed Matter - Lecture 2

13/14 PSI - Condensed Matter - Lecture 4

13/14 PSI - Quantum Field Theory II - Lecture 4

Bulk-boundary correspondence in PEPS

Spin and Long-Range Forces: The Unfinished Tale of the Last Massless Particle

13/14 PSI - Condensed Matter - Lecture 3

13/14 PSI - Quantum Field Theory II - Lecture 3

General Relativity for Cosmology - Lecture 17

Quantum mechanics as an operationally time symmetric probabilistic theory

On Scale and Conformal Invariance in Four Dimensions

Baryogenesis from WIMPs

Is there evidence for additional neutrino species from cosmology?

13/14 PSI - Condensed Matter - Lecture 2