Search Talks

9985 - 9996 of 16860 Results

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 Foundations
On Scale and Conformal Invariance in Four Dimensions

Anatoly Dymarsky Skolkovo Institute of Science and Technology
November 12, 2013

PIRSA:13110068
Quantum Fields and Strings
Baryogenesis from WIMPs
November 12, 2013

PIRSA:13110046
Particle Physics
Is there evidence for additional neutrino species from cosmology?

Stephen Feeney
November 12, 2013

PIRSA:13110083
Cosmology
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 - Quantum Field Theory II - Lecture 2

Francois David CEA Saclay

November 12, 2013

PIRSA:13110009
A universal Hamiltonian simulator: the full characterization

Gemma De Las Cuevas Universität Innsbruck
November 11, 2013

PIRSA:13110065
Quantum Information
New Constraints on the Amplitude of Cosmic Density Fluctuations and Intracluster Gas from the Thermal SZ Signal Measured by Planck and ACT
November 11, 2013

PIRSA:13110081
Cosmology
13/14 PSI - Condensed Matter - Lecture 1
- Anushya Chandran Perimeter Institute for Theoretical Physics
- Roger Melko University of Waterloo
- Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics
November 11, 2013

PIRSA:13110027
13/14 PSI - Quantum Field Theory II - Lecture 1

Francois David CEA Saclay

November 11, 2013

PIRSA:13110008

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 Foundations
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
Quantum Fields and Strings
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
Particle 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
Cosmology
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
13/14 PSI - Quantum Field Theory II - Lecture 2

Francois David CEA Saclay

November 12, 2013

PIRSA:13110009
A universal Hamiltonian simulator: the full characterization

Gemma De Las Cuevas Universität Innsbruck
November 11, 2013

PIRSA:13110065
Quantum Information
We show that if the ground state energy problem of a classical spin model is NP-hard, then there exists a choice parameters of the model such that its low energy spectrum coincides with the spectrum of \emph{any} other model, and, furthermore, the corresponding eigenstates match on a subset of its spins. This implies that all spin physics, for example all possible universality classes, arise in a single model. The latter property was recently introduced and called ``Hamiltonian completeness'', and it was shown that several different models had this property. We thus show that Hamiltonian completeness is essentially equivalent to the more familiar complexity-theoretic notion of NP-completeness. Additionally, we also show that Hamiltonian completeness implies that the partition functions are the same. These results allow us to prove that the 2D Ising model with fields is Hamiltonian complete, which is substantially simpler than the previous examples of complete Hamiltonians. Joint work with Toby Cubitt.
New Constraints on the Amplitude of Cosmic Density Fluctuations and Intracluster Gas from the Thermal SZ Signal Measured by Planck and ACT
November 11, 2013

PIRSA:13110081
Cosmology
Galaxy clusters form from the rarest peaks in the initial matter distribution, and hence are a sensitive probe of the amplitude of density fluctuations (sigma_8), the amount of matter in the universe, and the growth rate of structure. Galaxy clusters have the potential to constrain dark energy and neutrino masses. However, cluster cosmology is currently limited by systematic uncertainties due to poorly understood intracluster gas physics. I will present new statistical approaches to understand clusters and improve their cosmological constraining power through the thermal Sunyaev-Zel'dovich (tSZ) effect. First, I will describe a forthcoming first detection of the cross-correlation of the tSZ signal reconstructed from Planck data with the large-scale matter distribution traced by the Planck CMB lensing potential. This statistic measures the amount of hot gas found in moderately massive groups and clusters (M ~ 10^13-10^14.5 M_sun), a mass scale below that probed by direct cluster detections. Second, I will describe the first measurement of the PDF of the tSZ field using ACT 148 GHz maps. This measurement contains information from all (zero-lag) moments of the tSZ field, beyond simply the 2- or 3-point functions. It is a very sensitive probe of sigma_8 and may also provide a method with which to break the degeneracy between sigma_8 and uncertainties in the physics of the intracluster gas.
13/14 PSI - Condensed Matter - Lecture 1
- Anushya Chandran Perimeter Institute for Theoretical Physics
- Roger Melko University of Waterloo
- Xiao-Gang Wen Massachusetts Institute of Technology (MIT) - Department of Physics
November 11, 2013

PIRSA:13110027
13/14 PSI - Quantum Field Theory II - Lecture 1

Francois David CEA Saclay

November 11, 2013

PIRSA:13110008

Title	Date	Collection	Type	Info
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
13/14 PSI - Quantum Field Theory II - Lecture 2	2013‑11‑12	13/14 PSI - Quantum Field Theory II	Course	View details
A universal Hamiltonian simulator: the full characterization	2013‑11‑11	Perimeter Institute Quantum Discussions	Scientific Series	View details
New Constraints on the Amplitude of Cosmic Density Fluctuations and Intracluster Gas from the Thermal SZ Signal Measured by Planck and ACT	2013‑11‑11	Cosmology and Gravitation	Scientific Series	View details
13/14 PSI - Condensed Matter - Lecture 1	2013‑11‑11	13/14 PSI - Condensed Matter	Course	View details
13/14 PSI - Quantum Field Theory II - Lecture 1	2013‑11‑11	13/14 PSI - Quantum Field Theory II	Course	View details

Search Talks

Format results