Talks

12757 - 12768 of 20114 Results

12/13 PSI - Explorations on Quantum Information Lecture 5

David Cory Institute for Quantum Computing (IQC)

March 22, 2013

PIRSA:13030058

Quantum Physics
Advanced General Relativity - Lecture 18

Rafael Sorkin Perimeter Institute for Theoretical Physics

March 21, 2013

PIRSA:13030022
Particle Acceleration by Magnetic Reconnection in Striped Pulsar Winds and Relativistic Jets

Lorenzo Sironi Columbia University

March 21, 2013

PIRSA:13030078

General Relativity & Quantum Cosmology
12/13 PSI - Explorations in Particle Theory Lecture 4

David Morrissey TRIUMF

March 21, 2013

PIRSA:13030068

High Energy Physics
12/13 PSI - Explorations on Quantum Information Lecture 4

David Cory Institute for Quantum Computing (IQC)

March 21, 2013

PIRSA:13030057

Quantum Physics
Frustrated Magnets and Quantum Spin Liquids

Steven White University of California, Irvine

March 20, 2013

PIRSA:13030097

Condensed Matter
12/13 PSI - Explorations in Particle Theory Lecture 3

David Morrissey TRIUMF

March 20, 2013

PIRSA:13030067

High Energy Physics
12/13 PSI - Explorations on Quantum Information Lecture 3

David Cory Institute for Quantum Computing (IQC)

March 20, 2013

PIRSA:13030056

Quantum Physics
Advanced General Relativity - Lecture 17

Rafael Sorkin Perimeter Institute for Theoretical Physics

March 19, 2013

PIRSA:13030020
Evidence for a new particle on the worldsheet of the QCD flux tube

Sergei Dubovsky New York University (NYU)

March 19, 2013

PIRSA:13030109

High Energy Physics
Learning what the Higgs is mixed with

Kunal Kumar Carleton University

March 19, 2013

PIRSA:13030089

High Energy Physics
The Effective Field Theory of Large Scale Structures

Enrico Pajer Utrecht University

March 19, 2013

PIRSA:13030110

Astrophysics

12/13 PSI - Explorations on Quantum Information Lecture 5

David Cory Institute for Quantum Computing (IQC)

March 22, 2013

PIRSA:13030058

Quantum Physics
Advanced General Relativity - Lecture 18

Rafael Sorkin Perimeter Institute for Theoretical Physics

March 21, 2013

PIRSA:13030022
Particle Acceleration by Magnetic Reconnection in Striped Pulsar Winds and Relativistic Jets

Lorenzo Sironi Columbia University

March 21, 2013

PIRSA:13030078

General Relativity & Quantum Cosmology

The relativistic wind of pulsars consists of toroidal stripes of opposite magnetic field polarity, separated by current sheets of hot plasma. By means of 2D and 3D particle-in-cell simulations, we investigate particle acceleration and magnetic field dissipation at the termination shock of a striped pulsar wind. At the shock, the flow compresses and the alternating fields annihilate by driven magnetic reconnection. Irrespective of the stripe wavelength "lambda" or the wind magnetization "sigma" (in the regime sigma>>1 of magnetically-dominated flows), shock-driven reconnection transfers all the magnetic energy of the alternating fields to the particles. As the value of lambda/(r_L*sigma) increases (here, r_L is the relativistic Larmor radius in the wind), the post-shock spectrum passes from a thermal Maxwellian to a flat power-law tail with slope around -1.5, populated by particles accelerated by the reconnection electric field. The limit lambda/(r_L*sigma)>>1 is realized in relativistic jets, where kink instabilities may seed the conditions for magnetic reconnection. Here, we find that the particle spectrum in the current sheet approaches a flat power-law tail with slope between -1.5 and -2, regardless of the conditions in the jet. The spectrum extends to higher energies for larger magnetizations or colder plasma temperatures, everything else being fixed. Our results place important constraints on the emission models of Pulsar Wind Nebulae and magnetically-dominated astrophysical jets.
12/13 PSI - Explorations in Particle Theory Lecture 4

David Morrissey TRIUMF

March 21, 2013

PIRSA:13030068

High Energy Physics
12/13 PSI - Explorations on Quantum Information Lecture 4

David Cory Institute for Quantum Computing (IQC)

March 21, 2013

PIRSA:13030057

Quantum Physics
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.
12/13 PSI - Explorations in Particle Theory Lecture 3

David Morrissey TRIUMF

March 20, 2013

PIRSA:13030067

High Energy Physics
12/13 PSI - Explorations on Quantum Information Lecture 3

David Cory Institute for Quantum Computing (IQC)

March 20, 2013

PIRSA:13030056

Quantum Physics
Advanced General Relativity - Lecture 17

Rafael Sorkin Perimeter Institute for Theoretical Physics

March 19, 2013

PIRSA:13030020
Evidence for a new particle on the worldsheet of the QCD flux tube

Sergei Dubovsky New York University (NYU)

March 19, 2013

PIRSA:13030109

High Energy Physics

We propose a new approach for the calculation of the spectrum of excitations of QCD flux tubes. It relies on the fact that the worldsheet theory is integrable at low energies. With this approach, energy levels can be calculated for much shorter flux tubes than was previously possible, allowing for a quantitative comparison with existing lattice data. The improved theoretical control makes it manifest that existing lattice data provides strong evidence for a new pseudoscalar particle localized on the QCD fluxtube - the worldsheet axion.
Learning what the Higgs is mixed with

Kunal Kumar Carleton University

March 19, 2013

PIRSA:13030089

High Energy Physics

The Standard Model Higgs boson may be mixed with another scalar that does not couple singly to gauge bosons or fermions. The electroweak quantum numbers of such an additional scalar can be determined by measuring the quartic Higgs-Higgs-vector-vector couplings, which contribute—along with the coveted triple Higgs coupling—to double Higgs production in e+e− collisions. We show that simultaneous sensitivity to the quartic Higgs-Higgs-vector-vector coupling and the triple Higgs coupling can be obtained using measurements of the double Higgs production cross section at two different e+e− center-of-mass energies. Kinematic distributions of the two Higgs bosons in the final state could provide additional discriminating power.
The Effective Field Theory of Large Scale Structures

Enrico Pajer Utrecht University

March 19, 2013

PIRSA:13030110

Astrophysics

An analytical understanding of large-scale matter inhomogeneities is an important cornerstone of our cosmological model and helps us interpreting current and future data. The standard approach, namely Eulerian perturbation theory, is unsatisfactory for at least three reasons: there is no clear expansion parameter since the density contrast is not small everywhere; it does not consistently account for deviations at large scales from a perfect pressureless fluid induced by short-scale non-linearities; for generic initial conditions, loop corrections are UV divergent, making predictions cutoff dependent and hence unphysical. I will present the systematic construction of an Effective Field Theory of Large Scale Structures and show that it successfully addresses all of the above issues. The idea is to smooth the density and velocity fields on a scale larger than the non-linear scale. The resulting smoothed fields are then small everywhere and provide a well-defined small parameter for perturbation theory. Smoothing amounts to integrating out the short scales, whose non-linear dynamics is hard to describe analytically. Their effects on the large scales are then determined by the symmetries of the problems. They introduce additional terms in the fluid equations such as an effective pressure, dissipation and stochastic noise. These terms have exactly the right scale dependence to cancel all divergences at one loop, and this should hold at all loops.
I will present a clean example of the renormalization of the theory in an Einstein de Sitter universe with self-similar initial conditions and discuss the relative importance of loop and effective corrections.

Title	Date	Collection	Type	Info
12/13 PSI - Explorations on Quantum Information Lecture 5	2013‑03‑22	12/13 PSI - Explorations on Quantum Information	Course	View details
Advanced General Relativity - Lecture 18	2013‑03‑21	Elements of General Relativity	Course	View details
Particle Acceleration by Magnetic Reconnection in Striped Pulsar Winds and Relativistic Jets	2013‑03‑21	Strong Gravity	Scientific Series	View details
12/13 PSI - Explorations in Particle Theory Lecture 4	2013‑03‑21	12/13 PSI - Explorations in Particle Theory	Course	View details
12/13 PSI - Explorations on Quantum Information Lecture 4	2013‑03‑21	12/13 PSI - Explorations on Quantum Information	Course	View details
Frustrated Magnets and Quantum Spin Liquids	2013‑03‑20	Colloquium	Scientific Series	View details
12/13 PSI - Explorations in Particle Theory Lecture 3	2013‑03‑20	12/13 PSI - Explorations in Particle Theory	Course	View details
12/13 PSI - Explorations on Quantum Information Lecture 3	2013‑03‑20	12/13 PSI - Explorations on Quantum Information	Course	View details
Advanced General Relativity - Lecture 17	2013‑03‑19	Elements of General Relativity	Course	View details
Evidence for a new particle on the worldsheet of the QCD flux tube	2013‑03‑19	Quantum Fields and Strings	Scientific Series	View details
Learning what the Higgs is mixed with	2013‑03‑19	Particle Physics	Scientific Series	View details
The Effective Field Theory of Large Scale Structures	2013‑03‑19	Cosmology and Gravitation	Scientific Series	View details

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Format results

12/13 PSI - Explorations on Quantum Information Lecture 5

Advanced General Relativity - Lecture 18

Particle Acceleration by Magnetic Reconnection in Striped Pulsar Winds and Relativistic Jets

12/13 PSI - Explorations in Particle Theory Lecture 4

12/13 PSI - Explorations on Quantum Information Lecture 4

Frustrated Magnets and Quantum Spin Liquids

12/13 PSI - Explorations in Particle Theory Lecture 3

12/13 PSI - Explorations on Quantum Information Lecture 3

Advanced General Relativity - Lecture 17

Evidence for a new particle on the worldsheet of the QCD flux tube

Learning what the Higgs is mixed with

The Effective Field Theory of Large Scale Structures

12/13 PSI - Explorations on Quantum Information Lecture 5

Advanced General Relativity - Lecture 18

Particle Acceleration by Magnetic Reconnection in Striped Pulsar Winds and Relativistic Jets

12/13 PSI - Explorations in Particle Theory Lecture 4

12/13 PSI - Explorations on Quantum Information Lecture 4

Frustrated Magnets and Quantum Spin Liquids

12/13 PSI - Explorations in Particle Theory Lecture 3

12/13 PSI - Explorations on Quantum Information Lecture 3

Advanced General Relativity - Lecture 17

Evidence for a new particle on the worldsheet of the QCD flux tube

Learning what the Higgs is mixed with

The Effective Field Theory of Large Scale Structures