Colloquium

Displaying 361 - 372 of 599

Quoins versus Coins

Terry Rudolph
Imperial College London
March 27, 2013

PIRSA:13030000
Quantum Information
Supersymmetric gauge theory and the Yangian - continued

Kevin Costello
Perimeter Institute for Theoretical Physics

March 26, 2013

PIRSA:13030115
Dissecting holography with higher spins

Xi Yin
Harvard University
March 25, 2013

PIRSA:13030098
Quantum Fields and Strings
Supersymmetric gauge theory and the Yangian

Kevin Costello
Perimeter Institute for Theoretical Physics

March 25, 2013

PIRSA:13030114
Frustrated Magnets and Quantum Spin Liquids

Steven White
University of California, Irvine
March 20, 2013

PIRSA:13030097
Condensed Matter
The Higgs confronts 3 universes at the LHC

Markus Luty
University of California, Davis
March 13, 2013

PIRSA:13030095
Particle Physics
Rethinking Cosmology
March 06, 2013

PIRSA:13030079
Cosmology
Non-perturbative problems in gauge theories: N=2 quiver QCD

Vasily Pestun
Institute for Advanced Study (IAS)
March 06, 2013

PIRSA:13030103
Quantum Fields and Strings
Getting the Most out of a Black Hole

Alexander Tchekhovskoy
Princeton University
March 04, 2013

PIRSA:13030102
Cosmology
Quantum Gravity as Random Geometry

Vincent Rivasseau
University of Paris-Saclay
February 27, 2013

PIRSA:13020132
Quantum Gravity
Beyond Massive Gravity

Rachel Rosen
Carnegie Mellon University
February 25, 2013

PIRSA:13020134
Cosmology
The Evolution of Quasars with Cosmic Time

Michael Strauss
Princeton University

February 20, 2013

PIRSA:13020120

Quoins versus Coins

Terry Rudolph
Imperial College London
March 27, 2013

PIRSA:13030000
Quantum Information
Human monkeys are used to thinking about the problem of choosing from a set of objects according to some desired, biased, probability distribution. Just think about how you chose your partner(s). Even when it is easy for you to do such a sampling, it can be difficult to do a quantum sampling (Q-Sampling) of the same distribution. By Q-Sampling I mean the creation of a coherent superposition of states of such objects whose amplitudes are the (square roots of) of the specified distribution. In this talk I will discuss what we do know about this problem, why it is interesting, and will discuss how it can let us achieve tasks with quantum information that are provably impossible classically.
Supersymmetric gauge theory and the Yangian - continued

Kevin Costello
Perimeter Institute for Theoretical Physics

March 26, 2013

PIRSA:13030115

I'll explain a new connection between supersymmetric gauge theories and the Yangian. The main result is that a twisted, deformed version of the pure N=1 supersymmetric gauge theory is controlled by the Yangian, in the same way that Chern-Simons theory is controlled by the quantum group. This result is used to give an exact calculation, in perturbation theory, of the expectation value of a certain net of n+m Wilson operators in the deformed N=1 gauge theory. This expectation value coincides with the partition function of a spin-chain integrable lattice model on an n-by-m doubly-periodic lattice.
Dissecting holography with higher spins

Xi Yin
Harvard University
March 25, 2013

PIRSA:13030098
Quantum Fields and Strings
The holographic correspondence is a powerful duality between a quantum theory of gravity and a quantum gauge theory in one lower space-time dimension. Higher spin gravity theories, i.e. gravity theories that also contain (gauge) fields of spins greater than 2, play a special role in holography. I will explain consistent interacting higher spin gravity theories in anti-de Sitter space, their duality with gauged conformal vector models, and their connection to string theory.
Supersymmetric gauge theory and the Yangian

Kevin Costello
Perimeter Institute for Theoretical Physics

March 25, 2013

PIRSA:13030114

I'll explain a new connection between supersymmetric gauge theories and the Yangian. The main result is that a twisted, deformed version of the pure N=1 supersymmetric gauge theory is controlled by the Yangian, in the same way that Chern-Simons theory is controlled by the quantum group. This result is used to give an exact calculation, in perturbation theory, of the expectation value of a certain net of n+m Wilson operators in the deformed N=1 gauge theory. This expectation value coincides with the partition function of a spin-chain integrable lattice model on an n-by-m doubly-periodic lattice.
Frustrated Magnets and Quantum Spin Liquids

Steven White
University of California, Irvine
March 20, 2013

PIRSA:13030097
Condensed Matter
A quantum spin liquid is a solid whose atoms have magnetic moments but, because of quantum fluctuations, these moments fluctuate like a liquid even at zero temperature. Two dimensional spin liquids have been suggested as a way to produce high temperature superconductivity, and to build quantum computers. Just as helium is the only element which is a liquid at zero temperature, 2D spin liquids have been extremely difficult to find, despite decades of effort, raising the question, do realistic spin liquids even exist?
Recently, apparent spin liquids have been found experimentally, stimulating theoretical work to find simple model Hamiltonians of frustrated spin systems that have spin liquid ground states.

In this talk, I will give a broad overview of spin liquids and then focus on our simulations of the kagome Heisenberg model, a simple, realistic model of some of the recent experimental spin liquids, where we find a spin liquid ground state.
The Higgs confronts 3 universes at the LHC

Markus Luty
University of California, Davis
March 13, 2013

PIRSA:13030095
Particle Physics
The recent discovery of the Higgs boson is a fundamental advance in particle physics. This talk gives a theorist's perspective of the significance of this discovery. The Higgs boson was proposed in the 1960s, but it is best understood in the context of the quest to understand the weak interactions, which began with Fermi's theory of weak interactions almost 80 years ago. This has led to three very different paradigms for the structure of fundamental interactions at the TeV scale: supersymmetry, compositeness/extra dimensions, and anthropic selection. The Large Hadron Collider is the experimentum crucis for deciding between these different possible universes, and the discovery of the Higgs is a crucial clue. This talk will describe these paradigms, the implications of the Higgs discovery for them, and the outlook for further discoveries that would decide between them.
Rethinking Cosmology
March 06, 2013

PIRSA:13030079
Cosmology
This talk will begin by discussing one by one the various reasons why cosmologists today consider the big bang inflationary cosmology to be the leading, if not proven, theory of the universe and then explaining why each of these reasons is flawed. This leads naturally to the question: what is the alternative? Understanding the flaws helps point the way.
Non-perturbative problems in gauge theories: N=2 quiver QCD

Vasily Pestun
Institute for Advanced Study (IAS)
March 06, 2013

PIRSA:13030103
Quantum Fields and Strings
Non-perturbative effects are responsible for the essential dynamical features of the four-dimensional gauge theories such as QCD. The N=2 supersymmetric four-dimensional theories are an interesting class of models in which non-perturbative computations can be carried out with arbitrary precision using localization of the path integrals. I will explain the new exact non-perturbative results and the relation to classical and quantum integrable systems for a large class of N=2 supersymmetric QCD.
Getting the Most out of a Black Hole

Alexander Tchekhovskoy
Princeton University
March 04, 2013

PIRSA:13030102
Cosmology
As black holes accrete surrounding gas, they often produce relativistic, collimated outflows, or jets. Jets are expected to form in the black hole vicinity making them powerful probes of strong-field gravity. However, how jet properties are connected to black hole and accretion flow properties has been unclear. Recent progress in computer simulations of black hole accretion enables studies of jet formation in unprecedented detail. For the first time, 3D general relativistic magnetohydrodynamic numerical simulations allow one to determine the maximum efficiency with which accretion onto black holes can power relativistic jets. I will present the dependence of this maximum efficiency on black hole spin and discuss how this dependence allows one to probe strong-field gravity. In realistic astrophysical systems, the angular momentum vector of the accretion flow can be tilted relative to the spin of the black hole. I will present the first simulations of jets from such tilted accretion systems and discuss their observational signatures.
Quantum Gravity as Random Geometry

Vincent Rivasseau
University of Paris-Saclay
February 27, 2013

PIRSA:13020132
Quantum Gravity
Matrix models, random maps and Liouville field theory are prime tools which connect random geometry and quantum gravity in two dimensions. The tensor track is a new program to extend this connection to higher dimensions through the corresponding notions of tensor models, colored triangulations and tensor group field theories.
Beyond Massive Gravity

Rachel Rosen
Carnegie Mellon University
February 25, 2013

PIRSA:13020134
Cosmology
In the last few years there has been a burst of progress in the field of massive gravity. The construction of consistent theories in which the graviton has a small mass has in turn led to the development a new family of compelling, consistent low-energy modifications of General Relativity. These theories improve our understanding of the interplay between gravity and particle physics and provide new approaches to solving the cosmological constant problem. In this talk I will review these recent developments. I will discuss the search among these new theories for a symmetry that has the potential to address the cosmological constant problem.
The Evolution of Quasars with Cosmic Time

Michael Strauss
Princeton University

February 20, 2013

PIRSA:13020120

While the luminosity and mass distributions of quasars has evolved dramatically with cosmic time, the physical properties of quasars of a given luminosity are remarkably independent of redshift. I will describe recent results on the spectra of luminous quasars, the dark matter halos in which they sit, and the intergalactic medium of their host galaxies, that are essentially indistinguishable from moderate redshifts to z>6. The one property apparently unique to the highest-redshift quasars is that some small fraction show evidence for having very little infrared excess from hot dust. Dust obscuration is another theme in quasar studies; an appreciable fraction of the growth of black holes may be hidden at optical wavelengths by dust. I will describe searches for obscured quasars at high redshift and low, and studies of their demographics and physical properties.

Title	Speaker(s)	Date	Talk Type	Info
Quoins versus Coins	Terry Rudolph	2013-03-27	Scientific Series	View details
Supersymmetric gauge theory and the Yangian - continued	Kevin Costello	2013-03-26	Scientific Series	View details
Dissecting holography with higher spins	Xi Yin	2013-03-25	Scientific Series	View details
Supersymmetric gauge theory and the Yangian	Kevin Costello	2013-03-25	Scientific Series	View details
Frustrated Magnets and Quantum Spin Liquids	Steven White	2013-03-20	Scientific Series	View details
The Higgs confronts 3 universes at the LHC	Markus Luty	2013-03-13	Scientific Series	View details
Rethinking Cosmology		2013-03-06	Scientific Series	View details
Non-perturbative problems in gauge theories: N=2 quiver QCD	Vasily Pestun	2013-03-06	Scientific Series	View details
Getting the Most out of a Black Hole	Alexander Tchekhovskoy	2013-03-04	Scientific Series	View details
Quantum Gravity as Random Geometry	Vincent Rivasseau	2013-02-27	Scientific Series	View details
Beyond Massive Gravity	Rachel Rosen	2013-02-25	Scientific Series	View details
The Evolution of Quasars with Cosmic Time	Michael Strauss	2013-02-20	Scientific Series	View details

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