Scientific Series

Displaying 3517 - 3528 of 5085

Rethinking Cosmology
March 06, 2013

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

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

PIRSA:13030103
High Energy Physics
Thermodynamical Property of Entanglement Entropy for Excited States and Holographic Local Quench

Masahiro Nozaki University of Chicago
March 05, 2013

PIRSA:13030081
High Energy Physics
The correlator of two vector and one axial current in QCD

Kirill Melnikov Johns Hopkins University
March 05, 2013

PIRSA:13030099
High Energy Physics
Getting the Most out of a Black Hole

Alexander Tchekhovskoy Princeton University
March 04, 2013

PIRSA:13030102
Astrophysics
Gravitational anomaly and topological phases

Shinsei Ryu University of Illinois at Urbana-Champaign (UIUC)
February 28, 2013

PIRSA:13020148
Condensed Matter
Exploiting the Strong Gravitational Fields of Neutron Stars to Measure their Properties

Dimitrios Psaltis University of Arizona
February 28, 2013

PIRSA:13020126
General Relativity & Quantum Cosmology
Quantum Gravity as Random Geometry

Vincent Rivasseau University of Paris-Saclay
February 27, 2013

PIRSA:13020132
General Relativity & Quantum Cosmology
The universe as a process of unique events

Lee Smolin Perimeter Institute for Theoretical Physics
February 26, 2013

PIRSA:13020146
Quantum Physics
Quantum Computation vs. Firewalls

Daniel Harlow Massachusetts Institute of Technology (MIT)
February 26, 2013

PIRSA:13020138
Quantum Physics

High Energy Physics
DMRG Studies on the Spin Liquid Ground State of the Kagome Model

Stefan Depenbrock Ludwig-Maximilians-Universität München (LMU)
February 26, 2013

PIRSA:13020147
Condensed Matter
FERMI 130 GeV Line: Dark Interpretations

Matthew McCullough Massachusetts Institute of Technology (MIT)
February 26, 2013

PIRSA:13020150
High Energy Physics

Rethinking Cosmology
March 06, 2013

PIRSA:13030079
Astrophysics
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
High Energy Physics
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.
Thermodynamical Property of Entanglement Entropy for Excited States and Holographic Local Quench

Masahiro Nozaki University of Chicago
March 05, 2013

PIRSA:13030081
High Energy Physics
In this talk, we will describe our recent work. Recently, we focus on the thermodynamical property and time dependence of entanglement entropy. Using holography, we found that the entanglement entropy for a very small subsystem obeys a property which is analogous to the first law of thermodynamics when we excite the system. In relativistic setups, its effective temperature is proportional to the inverse of the subsystem size. This provides a universal relationship between the energy and the amount of quantum information. Moreover, we will propose a new holographic model of local quench and describe some results which we got by using this model. This talk is based on arXiv:1212.1164 [hep-th] and arXiv:1302.5703 [hep-th].
The correlator of two vector and one axial current in QCD

Kirill Melnikov Johns Hopkins University
March 05, 2013

PIRSA:13030099
High Energy Physics
It is known that the correlator of one axial and two vector currents, that receives leading contributions through one-loop fermion triangle diagrams, is not modified by QCD radiative corrections at two loops. It was suggested that this non-renormalization of the VVA correlator persists in higher orders in perturbative QCD as well. To check this assertion, I compute the three-loop QCD corrections to the VAA-correlator using the technique of asymptotic expansions. I find that these corrections do not vanish and that they are proportional to the QCD beta-function. I will also review some properties of the VVA correlator that were discovered in recent years.
Getting the Most out of a Black Hole

Alexander Tchekhovskoy Princeton University
March 04, 2013

PIRSA:13030102
Astrophysics
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.
Gravitational anomaly and topological phases

Shinsei Ryu University of Illinois at Urbana-Champaign (UIUC)
February 28, 2013

PIRSA:13020148
Condensed Matter
Since the quantum Hall effect, the notion of topological phases of matter has been extended to those that are well-defined (or: ``protected'') in the presence of a certain set of symmetries, and that exist in dimensions higher than two. In the (fractional) quantum Hall effects (and in ``chiral'' topological phases in general), Laughlin's thought experiment provides a key insight into their topological characterization; it shows a close connection between topological phases and quantum anomalies. By taking various examples, I will demonstrate that quantum anomalies serve as a useful tool to diagnose (and even define) topological properties of the systems. For chiral topological phases in (2+1) dimensions and (3+1) dimensional topological superconductors, I will discuss topological responses of the system which involve a cross correlation between thermal transport, angular momentum, and entropy. We also argue that gravitational anomaly is useful to study symmetry protected topological phases in (2+1) dimensions.
Exploiting the Strong Gravitational Fields of Neutron Stars to Measure their Properties

Dimitrios Psaltis University of Arizona
February 28, 2013

PIRSA:13020126
General Relativity & Quantum Cosmology
Neutron stars possess the strongest gravitational fields among stellar objects in the Universe that are not surrounded by a horizon. This causes the emission from their surfaces to be strongly lensed and deformed. Two upcoming space X-ray missions, ESA's LOFT and NASA's NICER, aim to use observations of lightcurves from spinning neutron stars to map their gravitational fields as well as measure their masses and radii. In this talk, I will discuss some unexpected strong-field phenomena that affect gravitational lensing in the vicinity of neutron stars. I will then show how we can use these phenomena to measure strong-field frame dragging and break degeneracies in the measured neutron-star masses and radii.
Quantum Gravity as Random Geometry

Vincent Rivasseau University of Paris-Saclay
February 27, 2013

PIRSA:13020132
General Relativity & Quantum Cosmology
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.
The universe as a process of unique events

Lee Smolin Perimeter Institute for Theoretical Physics
February 26, 2013

PIRSA:13020146
Quantum Physics
Quantum Computation vs. Firewalls

Daniel Harlow Massachusetts Institute of Technology (MIT)
February 26, 2013

PIRSA:13020138
Quantum Physics

High Energy Physics
DMRG Studies on the Spin Liquid Ground State of the Kagome Model

Stefan Depenbrock Ludwig-Maximilians-Universität München (LMU)
February 26, 2013

PIRSA:13020147
Condensed Matter
I will present a density-matrix renormalization group (DMRG) study of the S=1/2 Heisenberg antiferromagnet on the kagome lattice to identify the conjectured spin liquid ground state. Exploiting SU(2) spin symmetry, which allows us to keep up to 16,000 DMRG states, we consider cylinders with circumferences up to 17 lattice spacings and find a spin liquid ground state with an estimated per site energy of -0.4386(5), a spin gap of 0.13(1), very short-range decay in spin, dimer and chiral correlation functions and finite topological entanglement consistent with the logarithm of 2, ruling out gapless, chiral or non-topological spin liquids. All this would provide strong evidence for a gapped topological Z_2 spin liquid.
FERMI 130 GeV Line: Dark Interpretations

Matthew McCullough Massachusetts Institute of Technology (MIT)
February 26, 2013

PIRSA:13020150
High Energy Physics
Last year strong evidence was claimed for a 130 GeV gamma ray line from the galactic center in the FERMI telescope data. In the first half of the talk I will review the status of the evidence, including recent suggestions which call it into question. In the second half of the talk, under the bold assumption that the line is a genuine signature of dark matter, I will review some of the properties required of dark matter to explain the line and the general features of models proposed to explain it. This second half will include material from recent work with Francesco D'Eramo and Jesse Thaler (arxiv:1210.7817), which suggests that the line is readily explained by dark matter "semi-annihilation" rather than the standard annihilation interpretation.

Title	Speaker(s)	Date	Talk Type	Info link
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
Thermodynamical Property of Entanglement Entropy for Excited States and Holographic Local Quench	Masahiro Nozaki	2013-03-05	Scientific Series	View details
The correlator of two vector and one axial current in QCD	Kirill Melnikov	2013-03-05	Scientific Series	View details
Getting the Most out of a Black Hole	Alexander Tchekhovskoy	2013-03-04	Scientific Series	View details
Gravitational anomaly and topological phases	Shinsei Ryu	2013-02-28	Scientific Series	View details
Exploiting the Strong Gravitational Fields of Neutron Stars to Measure their Properties	Dimitrios Psaltis	2013-02-28	Scientific Series	View details
Quantum Gravity as Random Geometry	Vincent Rivasseau	2013-02-27	Scientific Series	View details
The universe as a process of unique events	Lee Smolin	2013-02-26	Scientific Series	View details
Quantum Computation vs. Firewalls	Daniel Harlow	2013-02-26	Scientific Series	View details
DMRG Studies on the Spin Liquid Ground State of the Kagome Model	Stefan Depenbrock	2013-02-26	Scientific Series	View details
FERMI 130 GeV Line: Dark Interpretations	Matthew McCullough	2013-02-26	Scientific Series	View details

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Format results

Rethinking Cosmology

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

Thermodynamical Property of Entanglement Entropy for Excited States and Holographic Local Quench

The correlator of two vector and one axial current in QCD

Getting the Most out of a Black Hole

Gravitational anomaly and topological phases

Exploiting the Strong Gravitational Fields of Neutron Stars to Measure their Properties

Quantum Gravity as Random Geometry

The universe as a process of unique events

Quantum Computation vs. Firewalls

DMRG Studies on the Spin Liquid Ground State of the Kagome Model

FERMI 130 GeV Line: Dark Interpretations

Rethinking Cosmology

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

Thermodynamical Property of Entanglement Entropy for Excited States and Holographic Local Quench

The correlator of two vector and one axial current in QCD

Getting the Most out of a Black Hole

Gravitational anomaly and topological phases

Exploiting the Strong Gravitational Fields of Neutron Stars to Measure their Properties

Quantum Gravity as Random Geometry

The universe as a process of unique events

Quantum Computation vs. Firewalls

DMRG Studies on the Spin Liquid Ground State of the Kagome Model

FERMI 130 GeV Line: Dark Interpretations