Talks

13849 - 13860 of 22673 Results

PHY 789 - Lecture 1

Niayesh Afshordi University of Waterloo

October 21, 2014

PIRSA:14100122
Numerical Study of a Bosonic Topological Insulator in Three Dimensions

Scott Geraedts California Institute of Technology

October 21, 2014

PIRSA:14100113

Condensed Matter
14/15 PSI - Conformal Field Theory - Lecture 11

Freddy Cachazo Perimeter Institute for Theoretical Physics

October 21, 2014

PIRSA:14100023
Disturbance in weak measurements and the difference between quantum and classical weak values

Asger Ipsen

October 21, 2014

PIRSA:14100114

Quantum Physics
Three-Point Function in N=4 SYM and Spin Vertex

Yunfeng Jiang

October 21, 2014

PIRSA:14100079

High Energy Physics
PHYS 781 - Lecture 8

Niayesh Afshordi University of Waterloo

October 21, 2014

PIRSA:14100054
Fundamental physics with muons

October 21, 2014

PIRSA:14100115
Schroedinger method as field theoretical model to describe structure formation

Cora Uhlemann Bielefeld University

October 21, 2014

PIRSA:14100076

Astrophysics
14/15 PSI - Statistical Mechanics - Lecture 11

Anton Burkov University of Waterloo

October 21, 2014

PIRSA:14100099
14/15 PSI - Quantum Field Theory I (A) - Lecture 11

Tibra Ali Perimeter Institute for Theoretical Physics

Dan Wohns Perimeter Institute for Theoretical Physics

October 21, 2014

PIRSA:14100042
14/15 PSI - Conformal Field Theory - Lecture 10

Freddy Cachazo Perimeter Institute for Theoretical Physics

October 20, 2014

PIRSA:14100022
14/15 PSI - Statistical Mechanics - Lecture 10

Anton Burkov University of Waterloo

October 20, 2014

PIRSA:14100098

PHY 789 - Lecture 1

Niayesh Afshordi University of Waterloo

October 21, 2014

PIRSA:14100122
Numerical Study of a Bosonic Topological Insulator in Three Dimensions

Scott Geraedts California Institute of Technology

October 21, 2014

PIRSA:14100113

Condensed Matter

We construct a model which realizes a (3+1)-dimensional symmetry-protected topological phase of bosons with U(1) charge conservation and time reversal symmetry, envisioned by A. Vishwanath and T. Senthil [PRX 4 011016]. Our model works by introducing an additional spin degree of freedom, and binding its hedgehogs to a species of charged bosons. We study the model using Monte Carlo and determine its bulk phase diagram; the phase where the bound states of hedgehogs and charges condense is the topological phase, and we demonstrate this by observing a Witten effect. We also study the surface phase diagram on a (2+1)-dimensional boundary between the topological and trivial insulators. We find a number of exotic phases on the surface, including exotic superfluids, a phase with a Hall conductivity quantized to half the value possible in 2D, and a phase with intrinsic topological order. We also find a new bulk phase with intrinsic topological order.
14/15 PSI - Conformal Field Theory - Lecture 11

Freddy Cachazo Perimeter Institute for Theoretical Physics

October 21, 2014

PIRSA:14100023
Disturbance in weak measurements and the difference between quantum and classical weak values

Asger Ipsen

October 21, 2014

PIRSA:14100114

Quantum Physics

The role of measurement induced disturbance in weak measurements is of central importance for the interpretation of the weak value. Uncontrolled disturbance can interfere with the postselection process and make the weak value dependent on the details of the measurement process. Here we develop the concept of a generalized weak measurement for classical and quantum mechanics. The two cases appear remarkably similar, but we point out some important differences. A priori it is not clear what the correct notion of disturbance should be in the context of weak measurements. We consider three different notions and get three different results: (1) For a `strong' definition of disturbance, we find that weak measurements are disturbing. (2) For a weaker definition we find that a general class of weak measurements are non-disturbing, but that one gets weak values which depend on the measurement process. (3) Finally, with respect to an operational definition of the `degree of disturbance', we find that the AAV weak measurements are the least disturbing, but that the disturbance is still non-zero.
Three-Point Function in N=4 SYM and Spin Vertex

Yunfeng Jiang

October 21, 2014

PIRSA:14100079

High Energy Physics

In this talk I will explain how to compute three-point functions of N=4 SYM theory in the planar limit for tree level and one-loop in perturbation theory. First I will recall how to formulate the problem of computing the three-point function of operators with determined R-charges in the language of integrable spin chains. In the su(2) sector, the tree-level three point function can be obtained in terms of determinants, whose large R-charge limit can be taken explicitly. Then I will report a systematic method to compute the su(2) three point function at higher loops. In particular, we are able to take the semi-classical limit, and we can compare our result with the calculation from string theory. In the Frolov-Tseytlin limit we find a perfect match at one-loop. Finally I will present a new formalism of computing three-point functions called the spin vertex formalism, which is the weak coupling counter-part of the string vertex in the string field theory. I will describe how to construct the spin vertex and discuss its important properties.
PHYS 781 - Lecture 8

Niayesh Afshordi University of Waterloo

October 21, 2014

PIRSA:14100054
Fundamental physics with muons

October 21, 2014

PIRSA:14100115

I will review applications of the muon as a probe for new phenomena. Topics to be discussed include the free muon decay and the determination of the Fermi constant; the anomalous magnetic moment of the muon; and searches for lepton flavor violation such as mu->e+gamma, mu->3e, and the muon-electron conversion, with special emphasis on the modification of the muon decay by the atomic binding.
Schroedinger method as field theoretical model to describe structure formation

Cora Uhlemann Bielefeld University

October 21, 2014

PIRSA:14100076

Astrophysics

We investigate large-scale structure formation of collisionless dark matter in the phase space description based on the Vlasov equation whose nonlinearity is induced solely by gravitational interaction according to the Poisson equation. Determining the time-evolution of density and velocity demands solving the full Vlasov hierarchy for the cumulants of the distribution function. In the presence of long-range interaction no consistent truncation is known apart from the dust model which is incapable of describing the formation of bound structures due to the inability to generate higher cumulants like velocity dispersion. Our goal is to find a simple ansatz for the phase space distribution function that approximates the full Vlasov distribution function and can serve as theoretical N-body double to replace the dust model. We present the Schroedinger method which is based on the coarse-grained Wigner probability distribution obtained from a wave function fulfilling the Schroedinger-Poisson equation as sought-after model. We show that its evolution equation approximates the Vlasov equation in a controlled way, cures the shell-crossing singularities of the dust model and is able to describe multi-streaming which is crucial for halo formation. This feature has already been employed in cosmological simulations of large-scale structure formation by Widrow & Kaiser (1993). We explain how the coarse-grained Wigner ansatz allows to calculate higher cumulants like velocity dispersion analytically from density and velocity in a self-consistent manner. On this basis we show that instead of solving the Vlasov-Poisson system one can use the Schrödinger method and solve the Schrödinger-Poission equation to directly determine density and velocity and all higher cumulants. As a first application we study the coarse-grained dust model, which is a limiting case of the Schrödinger method, within Eulerian and Lagrangian perturbation theory.
14/15 PSI - Statistical Mechanics - Lecture 11

Anton Burkov University of Waterloo

October 21, 2014

PIRSA:14100099
14/15 PSI - Quantum Field Theory I (A) - Lecture 11

Tibra Ali Perimeter Institute for Theoretical Physics

Dan Wohns Perimeter Institute for Theoretical Physics

October 21, 2014

PIRSA:14100042
14/15 PSI - Conformal Field Theory - Lecture 10

Freddy Cachazo Perimeter Institute for Theoretical Physics

October 20, 2014

PIRSA:14100022
14/15 PSI - Statistical Mechanics - Lecture 10

Anton Burkov University of Waterloo

October 20, 2014

PIRSA:14100098

Title	Date	Collection	Type	Info
PHY 789 - Lecture 1	2014‑10‑21		Course	View details
Numerical Study of a Bosonic Topological Insulator in Three Dimensions	2014‑10‑21	Quantum Matter	Scientific Series	View details
14/15 PSI - Conformal Field Theory - Lecture 11	2014‑10‑21	14/15 PSI - Conformal Field Theory	Course	View details
Disturbance in weak measurements and the difference between quantum and classical weak values	2014‑10‑21	Quantum Foundations	Scientific Series	View details
Three-Point Function in N=4 SYM and Spin Vertex	2014‑10‑21	Quantum Fields and Strings	Scientific Series	View details
PHYS 781 - Lecture 8	2014‑10‑21	PHYS 781 - Fundamentals of Astrophysics	Course	View details
Fundamental physics with muons	2014‑10‑21	Particle Physics	Scientific Series	View details
Schroedinger method as field theoretical model to describe structure formation	2014‑10‑21	Cosmology and Gravitation	Scientific Series	View details
14/15 PSI - Statistical Mechanics - Lecture 11	2014‑10‑21	14/15 PSI - Statistical Mechanics	Course	View details
14/15 PSI - Quantum Field Theory I (A) - Lecture 11	2014‑10‑21	14/15 PSI - Quantum Field Theory	Course	View details
14/15 PSI - Conformal Field Theory - Lecture 10	2014‑10‑20	14/15 PSI - Conformal Field Theory	Course	View details
14/15 PSI - Statistical Mechanics - Lecture 10	2014‑10‑20	14/15 PSI - Statistical Mechanics	Course	View details

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Format results

PHY 789 - Lecture 1

Numerical Study of a Bosonic Topological Insulator in Three Dimensions

14/15 PSI - Conformal Field Theory - Lecture 11

Disturbance in weak measurements and the difference between quantum and classical weak values

Three-Point Function in N=4 SYM and Spin Vertex

PHYS 781 - Lecture 8

Fundamental physics with muons

Schroedinger method as field theoretical model to describe structure formation

14/15 PSI - Statistical Mechanics - Lecture 11

14/15 PSI - Quantum Field Theory I (A) - Lecture 11

14/15 PSI - Conformal Field Theory - Lecture 10

14/15 PSI - Statistical Mechanics - Lecture 10

PHY 789 - Lecture 1

Numerical Study of a Bosonic Topological Insulator in Three Dimensions

14/15 PSI - Conformal Field Theory - Lecture 11

Disturbance in weak measurements and the difference between quantum and classical weak values

Three-Point Function in N=4 SYM and Spin Vertex

PHYS 781 - Lecture 8

Fundamental physics with muons

Schroedinger method as field theoretical model to describe structure formation

14/15 PSI - Statistical Mechanics - Lecture 11

14/15 PSI - Quantum Field Theory I (A) - Lecture 11

14/15 PSI - Conformal Field Theory - Lecture 10

14/15 PSI - Statistical Mechanics - Lecture 10